I do say, good sir, that you are thoroughly wrong.
You have to explain to me what 3D World has over NSMBU (aside from arbitrary stuff like "creativity" and "ambition") because I'm not seeing it.
3D World's problem is that it tries to be 2D Mario without accepting the boundaries of the genre. Instead of going for the open level design and freedom of control that previous 3D Marios usually have, 3D World instead tried to capture 2D Mario's compact and precise platforming and control, but being a 3D game in design simply means it inherently won't work, or rather it's not as precise and snappy as NSMBU. (Even ignoring its problem when it comes to judging the depth and distance because of the fixed camera)
So what is 3D World? It doesn't have the freedom of control that other 3D Marios have, nor is it as tight and responsive as your typical 2D Mario, including NSMBU.
And even ignoring that, 3D World's main strength, being the level design, simply doesn't reach the height of NSMBU's. See, NSMBU is brilliant. It's a no-nonsense, pure platformer that is lacking in any filler levels. So is 3D World. The main difference between them is that 3D World's level design's difficulty curve isn't as steady, the progression isn't as evident and it is not as cohesive. When you play NSMBU, every next level feels like it has connections to the last, it feels like natural progression, while the design of the level still manages to provide you with a unique challenge you haven't seen yet in the whole game. Each of 3D World's levels on the other hand feel like their own thing, with absolutely no connection whatsoever, as if each level its own minigame instead of being a central part of one whole game. That's what I mean when I say it doesn't feel cohesive.
It's not really just in terms of the environments (which is pretty random in 3D World whereas NSMBU sticks with its world theme), but to me, it's like the NSMBU developers say to themselves "alright, where do we go from there?" when finishing designing a level, whereas the 3D World devs say "OK, next idea on the board" when they're done designing a level. Get what I mean?
Not to say 3D World is bad (I love it), but it's not the direction I want 3D Mario to go from now on, especially when NSMBU does what it does better. Although I'd like it if NSMB adopts 3D World's multi character system just for the sake of replayability and variety, but NSMBU has challenge mode...and challenge mode is ****ing awesome.