You can't begrudge SOE wanting to expand and port the reasonably appreciated UL games to PS3. And the genre is under-represented, so yes, some people will want a 'Diablo clone in cave with crates*', though I'm sure they'd have a better looking option if available!
I've been debating whether or not I'll be desperate enough to pick up UL on PS3 at launch. I typically buy 3 games on launch and one of them will probably be Resistance. UT2007 might be the second if it has mouse and keyboard support. As for the third, I really don't know. I'm thinking a good Blu-Ray movie or three will be far more entertaining than this, though.
For those looking for hack 'n slash action, there's plenty to be had on the PC. Dungeon Siege II: Broken World is great, Titan Quest (or Diablo Greece, as one of my co-workers calls it) is also fun, and Mage Knight has just been released (though I don't know how good it is yet). Beyond that, there's plenty more on the horizon.
And let's not forget about Justice League Heroes -- sure to be one of the greatest superhero games ever created.