She was a wonderfully devious villain, and easy to love to hate. That said, she had tons of opportunities to not do the things she did. She totally deserved her fate.
 
I’m also of the mind that being aware of the outside world while being entrapped in stone was a Discord-only thing. It’s my headcanon that Chaos just simply won’t allow itself to be 100% contained.

Kids can be evil too. Cozy got her chance.

So you changed her character to make it look like she cared?

@Somber Star  
If your argument involves saying that Starlight wasn’t redeemed, you’re just simply factually incorrect.

@Somber Star
 

 
Okay, I know this isn’t the point, but uh… I’m pretty sure that Twilight could kill Starlight by herself if she wanted, especially by the point of S9. And even if she couldn’t, she has enough friends to accomplish that somehow. Starlight has shown no evidence she can really hurt Tirek at the level of power he was at, Twilight made him get knocked to the ground and lose a tooth. Starlight got defeated offscreen by Sombra, Twilight was successfully fighting back against him before her friends helped her kill him.
 
She’s not anywhere close to being that invincible. She’s flesh-and-blood just like everyone else, just with powerful magic.
 
And I’m pretty sure she got redeemed by now. She can 100% care about someone selflessly, it really pisses her off for someone to endanger others (AMOP, A Horse Shoe-In), or it really gets to her, the thought of her doing that (Student Counsel), she grew significantly more responsible with her great magical power, she went out of her way to take Chrysalis to a secluded area, and she unequivocally risked her well-being for a group of six (including Spike) that she once hated so that they could get away.
 
I’m not sure how that’s something that amounts to “never actually ‘redeemed,’” when the being she is at the end of the show is a lot different from her S5 self.

@Somber Star  
Starlight sure seemed to want to change her ways, that’s probably why she spied on Twilight and then almost destroyed the space-time continuum for petty revenge. Discord sure seamed to get better during his imprisonment in stone and Luna really seemed to not want to cause eternal night after spending a millenium on the moon. Oh wait…
 
These three (and perhaps Trixie), by that logic deserve to be imprisoned/reimprisoned just like Cozy was, but no, they were all given second (in Discord’s case third and fourth) chances. Kind of unfair if you ask me.
 
And seriously? A critarium for Starlight and Discord’s reformations is that their too powerfull/immortal to contain? In that case, Cozy wasn’t given a chance because she was not strong enough, therefore proving her point that friendship is power.
 
Also, the Sirens were also reformed.

Wow, the arguments in defense of Cozy here have sure gotten stupid. This is just like when a bunch of morons were defending Starlight back when she was the Equestrian equivalent of Stalin.
 
Starlight was never actually “redeemed”. It’s just that there’s literally nothing anypony can do to stop her without the use of a complete set of magical artifacts. But she’s trying, even if she doesn’t understand why, so that counts for something. This doesn’t apply to Cozy Glow, who can’t really do much on her own.
 
Discord is a literal god. The petrification thing will never work on him because he can just wait out anypony. He developed an attachment to Fluttershy because she was the first individual to show him kindness. This doesn’t apply to Cozy Glow because she’s mortal and as has been mentioned before, raised in the best possible environment.
 
Princess Luna’s redemption was so thorough that she underwent a physical transformation, and was still beating herself up over what she did long after the fact. Cozy Glow doesn’t have a “Nightmare Mode”, she’s just a little bitch 100% of the time, and as I mentioned previously, she’s unrepentant.
 
That one detail is actually the most important one when it comes to redemption-oriented morals: the state of repentance. Cozy Glow is not sorry for the harm she caused. She does not regret her actions. She is only upset by having failed.
 
You people need to stop letting your emotions dictate your judgment here and push you to give leeway to those who don’t deserve it. That’s how individuals like Cozy, Chrysalis, Sombra and the Sirens manipulate their victims and lead them to ruin. This show intended to teach morals and sell toys to children has had no less than four villain sets to demonstrate that fact (none of whom were redeemed) and still it somehow doesn’t get through your thick skulls.

Cozy Glow did nothing wrong.

Wow, the idiocy going on here is awe-inspiring.

So far, most people here are mixed in it! Both of them have great reasons why she stays or not in stone. ^^ She has given many chances, and she refused them all, so she sadly has to face terrible consequences for her actions, even though she is a filly. :D I still love Cozy Glow as a villainess. Just my opinion though! <3

@AC97  
Like how Starlight almost murdered three of her former townsponies? Or how Discord was only willing to help ponies entangled and in danger due to his plunder vines? Or how his chaotic nightmare of a rule would have effected ponies? Or how he only really cared about Tirek’s draining of ponies when Fluttershy was involved, only turning back when Tirek finally gave him a taste of his own medicine? How Luna simply didn’t care about the ramifications of an eternal night? How no one objected to Starlight offering Chrysalis a second chance right after she cocooned almost every important person in Equestria? Why would they even think of reforming such malicious and hatefull characters?
 
It’s not like they even tried chasing after Starlight, no wonder she escaped. Twilight can fly and teleport and one of her friends is literally the fastest pegasus around and they couldn’t have chased her down? Then again, they were willing to let Chrysalis run off despite even Discord being there.
 
And if Discord’s problem is not understanding friendship then the same problem goes for Cozy as well, Twilight even said so. And honestly, those classes were basically history lessons, animal care, PE and whatever the main six came up with. The actual friendshipping stuff happened in out of class activities, field trips and out of classroom demonstations Cozy didn’t often take part of.
 
How can they be sure Discord won’t try betraying them or “testing” them again? How do they know Starlight won’t return back to her old ways? How do they know Celestia and Luna won’t go insane during their retirement and turn evil or something?
 
I say again, Cozy was never given the same kind of chance as the reformed villains, despite it being inherintly safer to try and reform her due to her being a powerless kid. I mean, look at Rusty Bucket, Cozy was useless against him. And really? Better track record at manipulation then Discord? The same guy who made the former queen of race almost designed for deception, the centaur with a manipulative streak of his own and Cozy Glow believe he was Grogar? Who did all that while still maintaining his own life with his friends?
 
And why should redempion come out of usefullness? Are you saying Starlight wouldn’t have been worth reforming had she not been a powerfull unicorn? In that case Cozy would be right, friendship is power.

@AC97  

 
So… it’s not worth it because she isn’t useful like starlight or discord?  
Why a princess would want to help a child that will not be useful for her empire?  
That only make Cozy Glow right. This was never about friendship, this is about power and how use the friendship to get more power.  
Twilight really won in the friendship lottery with the princesses in her side

@Filliest filly
 
There’s a difference between “hates the character” and “likes the character being an absolutely unrepentant villain.”
 
Just like with Chrysalis and Tirek.

Wow. This place surely hate cozy glow

@Background Pony #BCE4
 

 
Why would they forgive her when she unquestionably almost caused deaths, she knew about it (she helped arranged the field trip too), and she was in the same room when “we barely caught everypony in time” was yelled by Rainbow Dash?
 

 
That isn’t quite what happened.
 
Starlight ran into the caves and got away. Cozy Glow tried to run away in a wide-open area.
 

 
Discord didn’t understand friendship on any level in his debut, beyond the surface-level understanding needed for him to corrupt them… with the assistance of mind-control. He outright cheated with Fluttershy, by brute-forcing it.
 
Now… Cozy Glow’s understanding of friendship, on the other hand? The only test she was shown to have failed (in her debut), she did so intentionally. Twilight and the others loved her, she went through the motions of helping students, and in the end, it all meant nothing to her. They were all just as disposable to her on an emotional level as a wet paper towel.
 
She was not a bad student. To get into her head, she’s someone who’d have to have sat through the likes of Applejack or Fluttershy talking about honesty and kindness, pass tests related to those, and then turn around and be evil.
 
How can they redeem someone who wants to murder them as much as Cozy Glow does, with as many things she’s given them to work with in regards to possibly redeeming her (nothing)?
 
How can they be sure she’d be genuine when she’s arguably got a better manipulation track than Discord, without her powers? She’s great at faking emotions.
 
Would her usefulness justify any efforts to redeem her? She’s not anywhere near as powerful as Discord, so no, probably not.

@AC97  
Pretty sure Discord knew he was a villain as well given his lack of care of the ponies he hurt during his reign/escape/siding with Tirek, yet he was given neumorous second chances while Cozy didn’t get a single one. Same with Starlight and Luna. Where was Starlight extending her hoof to her? When was she let out of Tartarus/unstoned by Celestia and forced to work with the a selected ponies attempt to reform her? Why didn’t Twilight let her run after her first defeat like she did with Starlight? Why didn’t Twilight make her a special student and give her the kind of attention she gave Starlight? Why wasn’t she immedietly forgiven for all her misdeeds like with Discord? I say again, she was never given a second chance like other villains got.
 
Would the reformed villains have turned into good guys had Twilight and friends not beaten them/stalled them? Would Discord have suddenly given up his villainous ways had Twilight just asked him to when he brainwashed her friends? I doupt any of them would have suddenly have a change of heart if some kind of a reformation wasn’t attempted with them. Double standards are a plenty.

Cozy Glow actually knows she’s evil, in case you missed it.
 
She literally sang a song about it in Frenemies, and declared the three of them as villains in the last two-parter, as something she takes pride in.
 
She does possess moral agency on account of her intellect, even manipulating others by framing the Student Six of doing the things she did, as if she knew that they’d see it as morally disgusting, not to mention how she dealt with Neighsay.
 
@Mihay
 

 

 
They did get the why. That second exchange was her chance to confide with Twilight, show any remorse, someone who’d cared about her before that, with any problems she had, but she threw a hissy fit, because she’s kinda empty like that.
 

@superfun  
…no she didn’t

@Jimp  
Well, there is Season 10 for the comics next year.

They gave you several chances, Cozy.  
You refused them all.

@Background Pony #BCE4
 
Ah but the final lesson was about how everything must change, this includes attitudes. And I’m also willing to bet Celestia and Luna never had any intentions of seeing a free Discord in future either.
 
It’s up to the fans to decide for themselves in the end, but given what we know how things often go in this world it’s a fair bet to assume they’re not beyond redemption.

@Jimp  
I’d like to agree, but as Discord said “together forever” without any objections from others.
 
A simple diologue change would have handled most of the problems with this.

Who’s to say Cozy or the others definitely won’t be redeemed? The series had to come to an end, which means canonically we may never know what fates they have beyond this, but do recall Discord spent a thousand years in stone before his redemption came. No reason to assume her petrification will be eternal either.

Caught together - punished together. Sad, but there is no alternative.  
There is much potential to write the story on including releasing and reforming them.

@Background Pony #088A  
So, reforming a villain should only be done if that villain could prove usefull in the future? That’s what friendship is about? I guess Cozy was right then, friendship is power.
 
And as Background Pony #088A says, Cozy is not a proven psychopath. She had a revelation on Mount Everhoof where she seemed to like helping others, she had no reason to pretend that she did. Starlight certainly didn’t seem to care about her former cult members when Twilight had to save them from her magic beam and she definetely didn’t seem to care when she almost killed Twilight and Spike after spending who knows how long spying on them. Discord didn’t care about the ponies his chaos might have harmed before his reformation and Luna didn’t seem to care about the consequences of an eternal night.
 
Cozy might have needed a bit more help to truly understand friendship then some other villains, but if someone like Discord could be “reformed” and given multiple second chances I don’t see why she should get none. It is simply unfair to her, and for that matter Chrysalis and Tirek as well.