Ah, I don't really want to argue this right now, but in terms of backdrops--perhaps, literally, there were three backdrop graphics total, but I misspoke--I meant backgrounds, and Galaxy used quite a bit of polygonal objects in its backgrounds that helped give it a better sense of space. The backgrounds of 3D World are more like the backdrops of 2D Mario--relatively static, faraway pictures that kind of give you a general sense of where the level takes place, and that's it.
And concerning the second point, I love Mario. I love 2D Mario, and I love 3D Mario.
But!
There comes a caveat here: I consider 2D Mario and 3D Mario to be completely separate beasts and I like them for very different--and usually diametrically opposed--reasons. I like run buttons in 2D Mario, but I think they're flat out heretical and annoying in 3D Mario. Time limits are tolerable to a point in 2D Mario, but I feel they have no place in 3D Mario outside of dedicated speedrun levels.