But again, if Mario had to always stay as it was, you wouldn't have gotten Mario 64 in the first place. Just because 3D Mario was one way in the past doesn't mean that's how it should always be. You can stop at any point in a franchise and mark a line of "everything before this is what the series should be" and it just becomes arbitrary. A lot of why early 3D Mario is why it was is because Nintendo wasn't able to translate platforming as well into 3D. But they have gotten better and better at it. Every 3D Mario after 64 puts a lot more effort into platforming in a 3D space. Sunshine is essentially the opposite of Mario 64 in that way, in that the game is almost always you needing to jump, walk tight paths, etc. Galaxy 1 and 2 built off of that, two more games that had huge focuses on 3D platforming, and then 3D Land and 3D World after.
3D Mario just isn't what I associate with conservative Nintendo. It's not a Dragon Quest, Pokemon kind of thing. It is where Nintendo has really spread their wings. I remember so much complaining about Sunshine being different from 64. Then I remember so much complaining that Galaxy 1 and 2 were different from 64. And then I remembered so much complaining that 3D Land and World were different from N64. There's always been that specific outcry against 3D Mario because of how much Nintendo likes to experiment.
3D Mario also being a genre is a problem in and of itself. I don't use 3D Mario as a genre, I use it as the very concept itself: Mario platforming in 3D. And with how resources are nowadays, it's extremely hard for Nintendo to appease everyone. If they have to make 3D Mario games similar to 64 until the end of time, they'd never get to do anything else. 64 did so many brand new things and changed so many Mario paradigms, so it would be pretty sad.
I also don't think any specific games should be considered "real" or "fake" 3D Mario games, that's weird.
Though, to make it clear: I don't want the next 3D Mario to be like 3D World. I don't want it to be like Odyssey, or 64, or Galaxy. I want it to be yet another new thing, in whatever form that is. If they have to pull another Mario 64 and kill some sacred cows, so be it.