I think they're trying to unify the mario design across platforms. So that mario, bowser, all enemies, etc share an approximately similar model on both Wii/WiiU and DS/3DS.
And considering that they went from ugly 3D background in NSMBWII to very nice drawn backgrounds in this title, I'd say they move in the right direction.
Besides, I don't think it'd be a good idea from a franchise point of view to give every title a unique artstyle.
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>>136822546was fantastic, but I don't think it would work for every Mario title. It fits the theme of "babies/picturebook". Just as Kirby's epic yarn wouldn't work for every Kirby title.
You need to have some sort of recognizable style with your series. I think nintendo is doing a pretty good job with that, actually.
I think if you introduce a unique artstyle, you have to justify it. With a theme that continues to be noticeable in gameplay, story and so on.
On the other hand, look at Zelda. It does work because it has a smaller core audience. And even there, everytime they introduce a new glorious artstyle, people are complaining.
