She’s the princess of an entire nation. One town getting attacked by a relatively mundane animal who has the element bearers to defend it is kind of low on her list of priorities

It never occured to me that the princesses could have been helping to stop the bugbear

No, I don’t think Jack took a shit to help any pony.  
Yes, this is how I read it just now. :/

Celestia:“Meh, it’s only a bugbear. Twilight can handle a single bugbear, no point risking my hooficure.”

@TexasUberAlles  
The problem with that though is that it makes you weak, you slack off and don’t regularly use your abilities you’re gonna get rusty and sloppy in your actions.
 
Just because you’re higher up doesn’t mean you should do less…or at the very least if you are going to do that at least do some practice here and there so when the times comes to where you have to do something and step in, you’re not going to fail harder then hard and then have your underlings save your ass…
 
It would be like a boxer win the championship then get lazy and do nothing for a year, and when he has to fight again he sucks balls cause he’s done no training in the past year. You haven’t done anything to keep in shape, that’s the problem. lol

@TexasUberAlles
 
Yeah, the latter is an explanation I can buy. The other princesses trusted the EOH to handle it and didn’t even worry.
 
After all, this New Kid and her underling friends have been saving Equestria from threats big and small. It’s not like Celestia would be concerned.

@Background Pony #6CC3  
it took the power of four alicorns combined to do that  
It only took one flight camp dropout and one laconic farmer to do this;  
 
…there’s bound to be a pretty steep jump in power level from there to millennia-old Alicorn princess.
 
the older more experienced princesses  
You mean the ones who were inside hitting the buffet and hangin’ out while The New Kid and some underlings dealt with a middling threat? Really, the most obvious answer is the one that’s been hit upon several times here already: the higher you are in an organization, the fewer problems are your problem, because you have employees to deal with it for you.

@TexasUberAlles
 
Yes, and it took the power of four alicorns combined to do that, which means it’s not likely to happen by accident, right?
 
My point is that Twilight was able to regulate her power as necessary, presumably without causing aditional damage. You’d think the older more experienced princesses would be able to do the same.

@Background Pony #6CC3  
on their own not something that would accidentally destroy the town like a nuclear bomb  

 
the only alicorn that can actually control how much power she uses  
I have a shotgun that throws an ounce of lead at 1300 feet per second; I don’t use it to swat flies, especially if there’s aready a kid standin’ there with a flyswatter in each hand.
 
We don’t know how powerful the Sky Panda actually was, other than “powerful enough to smash the corner off a house with no apparent effort or injury”, but that on its own suggests that it was a bit more of a threat than a typical Timber Wolf

@Background Pony #6CC3
 
The best explanation is that Celestia and Luna could control their power and fight things, but in this case they don’t have to. Let the Champions of Harmony do it and let Twi get some experience.
 
See? Simple.

@TexasUberAlles
 
That’s not a good comparison. We’ve seen all the alicorns use magic and even what all their combined power adds up to in Twilight’s kingdom. It’s powerful, but on their own not something that would accidentally destroy the town like a nuclear bomb.
 
Plus, unless you’re telling me that Twilight is the only alicorn that can actually control how much power she uses so that she doesn’t burn everything all the time, that’s a lame excuse.
 
And I assumed they’d used the Elements to beat Sombra, since it was before Luna was banished? Either way, that’s still not much better a track record.

@Background Pony #6CC3  
They are not nearly powerful enough to have to worry about destroying the town  
For a nation that’s so easily goaded into conflict and has so few qualms about swingin’ its, uh, military capacity around, how many times has the United States used atomic bombs in anger? There’s a fairly significant difference between not having power and not using power.
 
They have never won one in the show or even done that well without the Elements  

And the Princess who actually did something to protect the people was locked out of the wedding and forgotten about.
 
Poor purple one.

@lord_derp_herpington42
 
This is the lamest excuse I’ve ever heard.
 
Celestia and Luna are rulers, not fighters. They have never won one in the show or even done that well without the Elements. They are not nearly powerful enough to have to worry about destroying the town u_u

They didn’t want to accidentally destroy the whole town.  
I think the real question is just how well connected is Cranky that all three of them came to this wedding?

CEO of Chrysler don’t change his own oil, yo.

Actually, being Princess of Love, Cadance probably should prioritize weddings over monster attacks.

Well, they are rulers, not fighters. They have Champions of Equestria to deal with stuff like this…

It’s not like we’ve ever see Celestia win a fight. Or really even do that well.

Here’s the excuse  
Cadence had to deal with a Crying Shining Armor yet again  
Luna too busy on Video Games  
Celestia and her Cake fetish

@FSin  
If they actually got a little practice in by helping in some of these more minor problems, they probably wouldnt be as useless in protecting their lands…but then again, why do it yourself when someone else can do it for you…and for free…

KNowing Twilight she denied any asistance from Princesses

As the secret agent said, plausible deniability.

Your boss’ job is not your job.

@Velcro  
That makes sense. I don’t remember if that’s what happened, but it makes sense. If the fight was still going, Cadance, at the very least, would have rushed in to help zap it if the whole tatzlwurm thing (and in particular the part where fighting a giant monster made her feel better) is any indication.