The Mercy of Princess Celestia?

[Fractured 2,683]

Princess Celestia is a kind and loving ruler.
...No,really, as far as the show goes, it's more or less objective. She's saved Equestria countless times, runs an entire school, and raises the moon every day for her citizens; for 1,000 years, she even raised the moon. Ponies love her, and why wouldn't they? She's done all of these things without spilling a drop of blood.
But is that a good thing?
While she's never seen to have killed anypony, Celestia's punishments, are, in a way, worse than death. For Sombra, she turned his body to shadow, and cast him into the center of the earth:

 
Discord was sealed in stone, conscious, for longer than 1,000 years:

Nightmare Moon was sealed in/on the moon, presumably long enough to regret her actions. 

Tirek was locked in Tartarus for his crimes: 

These sentences tend to leave the condemned alive and conscious. They also tend to be indefinite; All of the aforementioned broke out through sheer coincidence, not through Celestia's doing. The question is: Would it be better is she had killed these ponies? Was there a better way she was just unable to see or use at the time? Is it a by-product of the elements; do you think they're unable to kill ponies, so she had to resort to some other method? Do you think the punishments fit the crime? This is a place to discuss everything regarding Celestia and her... unusual methods of punishment, and how it concerns the victims.

[pony.colin 156]

A more ridiculous sin is why everything evil conveniently breaks out of jail within a 1,000 year life time, you'd figure things would have been reasonably paced out more. 

 

And hey, really, chose to kill somepony or punish them by locking them away for a 1,000 years? That's a pretty good deal, well for Celestia anyways (1000 years of peace, but after that time is up, neighbourhood has to go a bit belly-up now), not so fun for the villain.

 

That and, plot conveniently needs villains to come back to further assist Twilicorn ascension fate.

 

1,000 years seems good. No other pony besides Celestia or Luna is going to live that long to see any of those villains come back in their lifetime except the ones at the end of the jailbreak life-sentence.

[M'aiq the Liar 5,804]

Well, since she never really says that she wants to imprison villains for a huge amount of time, and according to both snipits from the show, and the comics Celestia was somewhat actively trying to find a way to get her sister back form the moon (alot of speculation says this is why she let NMM return, because she knew that it was the only chance at once again seeing luna). So since she never really shows any malevolent intent, I would wager that it is just the elements doing what they do (handing out semi ironic prison sentences, as the ruler of the night was trapped in a spiritual stasis in the moon, the everchangeing Discord was turned into stone, the "dark magic" user Sombra was turned into literal darkness). Since all the punishments seem to be a form of dramatic irony, I would wager that Celestia herself has very little control in their effects, as they seem to run off medieval fable logic.