There's some decent "2D with 3D engine help" games out there -
Nippon Ichi's offerings on the PS2 are great strategy-RPG hybrids with wicked sense of humor. Disgaea in particular is a favorite.
BlazBlue is an amazing pure 2D fighter on the PS3 and Xbox 360 - since this is my favorite genre I was psyched to see the spiritual successor to Guilty Gear.
They're out there but there needs to be more. Imagine the crazy expansiveness you could make in 2D with today's horsepower.