Lemme first start by saying 3D World is an excellent game, but it's not the same as the 3D Mario games before it and that put some people off, which led to heavy forum debates. Fans of the game started defending it religiously, to the point that asking for another Galaxy acted as a triggering mechanism for confrontation. They will start dissecting the games coming up with reasons why 64, Sunshine and Galaxy were not the same in the first place with the silliest arguments. Passive agressive nit-picking and semantics is their MO.
When it's all so simple and easy with just 1 question. Is 3D World noticeably distinct than the others? Yes. It's not that hard to understand. It doesn't mean 3D World was bad.