Huge difference there. WOW talks about a specific setting. It's basically one giant, ongoing game. D&D is very different, and has been from its beginning. The idea that there's only one valid way to play, or that doing otherwise is somehow "wrong" or "unofficial" is belied by the explicit support for such in the PHB and DMG. Until you can explain that away, saying that the planar cosmology is a necessary part of D&D is just straight up wrong.
For me personally, the idea of having to play exclusively in the Great Wheel is repugnant enough that I would rather find a new system. I strongly dislike running games in that cosmology for many reasons. The freedom to create my own setting with my own cosmological rules and have it be just as valid as any other setting is one of the key parts I enjoy of D&D. And I'm not the only one. Of the dozens of people I've trained, almost none have decided to play in the "official" settings. This kind of setting snobbery, the One True Way-ism, is just as bad for the game as RAW snobbery, and just as wrong. Infinite Diversity in Infinite Combinations, not You Must Play Our Way.