Well a 2D game doesn't have to look like an old Amiga or any other older system, just because a game is in 2D doesn't mean it has to look crap.
There are sometimes certain "classic" games which are re-done in 3D, but in all honestly do you really think a game like say (thinking. . . . ) Rainbow Islands or some other cutesy platformer would be half as addictive in 3D, just seems to me that games need to be looking really good and in 3D, I'd welcome a Rainbow Islands style game in 2D with 16million colours and all the effects that could be produced!
Just my tuppence worth (again!!)