If you're even giving Ravenloft and Planescape as examples, why do you think D&D can accommodate stuff as Ravenloft AND Planescape but NOT anime?
You've said D&D is something else than anime, but then, what is D&D? Dark Sun? Planescape? Ravenloft? Forgotten Realms? Mystara? Eberron? A game with wacky space hamsters (i.e. Spelljammer)?
I'd rather say, WotC should do an animesque setting, allowing people accommodate that style, just as D&D can be used for Ravenloft, Planescape, Forgotten Realms, and Eberron. All of these four settings don't mix at all, but still they're D&D. Why isn't that the case with anime?
If D&D can have Spelljammers, it can have anime. Just don't try to use them all at once.
Cheers, LT.