http://i.imgur.com/UnxoKWp.png
That's a Geo. Yeah, sure, retarded lengths were taken, 3000 TP, Bolster, Malaise, Acumen, and used while it was casting. More for the lawls. :P
The design of Thf, and rogue type jobs as a whole in most games, has always been burst damage. They attack fast, though typically for low damage, then then unleash Back Stabs, Ambushes, Sneak Attacks, combos, etc. You have to stop thinking of these instances in the sense of "omg 30-50k damage?!? OP!!" and look at how things have progressed. Some boss type NMs have 1+ million HP, properly executed SCs can do 20-50k+ themselves (though Sam is typically the only job capable/given credit of being capable of this), and perhaps largest of all, the difference between buffed DDs and unbuffed DDs. SE specifically said these changes were going into place to make 1 handed DDs competitive
when they are poorly buffed. While I wouldn't advocate for it in game, I'd be interested in seeing spread sheet numbers of how Thf compares to other DDs when buffs are light/non-existent.
It's not so much that these instances are over powering, but rather that's the direction the game is going. All of this content is being made easy with these updates, jobs are being boosted to unprecedented degrees. Whether that's to make way for a new "easy mode" version of the game, or to give us these "fun" damage numbers only to re-balance us around them in the future is still to be seen.
WoW went through something very similar over the years. This last update, they "nerfed" everything, almost like starting over. I don't play so I don't know the details, but they felt that players doing 500k damage in a single attack was meaningless since you stopped paying attention to the numbers past the x00,000, the rest of the 0s were meaningless. Similar to that, when a character's HP was represented in the
hundreds of thousands, there was a lot of numbers that didn't matter. So they reset everyone's stats (numbers) to a new meaningful number, and rebalanced around it. Maybe you logged on one day to find you had 15k HP instead of 500k HP, but you were no longer getting hit for 300k either, but maybe 6-7k. Maybe your Fireball now did 10k damage instead of 400k damage, but trash mobs still died in two of them, etc.
These numbers are a representation of power creep though, rather than singular instances of a job being broken. Maybe we'll all be pushing out total DPS like this in the not so distant future, but NMs will regularly have 5+ mil HP and such. I don't really mind, the game has been a sandbox MMO for a good long while now. We'll always have situations where job x, WS y, gear z is considered OP by the player base.