Huh, I'm impressed at how much hatred some people can direct at 3D - it's like going 'fuck off with your 360s and PS3s - it's all just a graphical gimmick designed to make you shell out for a new console when you've already got one that can play games fine!' (Or, you know, words to that effect).
I found 3D Avatar and Up to be really immersive, much more so than 2D versions, so the application for gaming would be to take it to the next graphical level. It adds another level to presentation, beyond just how many polys you can have on-screen at a time, or how high-res your textures and bomb-maps are. I for one am happy to see new graphical effects come out, though I'm not planning on buying anything 3D in the foreseeable future, heh.
Also, mature 3D game tech + mature motion control system = next best thing to holodeck. That can't be a bad thing.
OT, first-person melee would be much improved, as would be platforming. Racing games could look seriously intense!