Is it only a techno limitation concerning the size and details of the levels ?
Mario 64 was already pioneering basically everything in the 3D platformers, and maybe even 3D games as a whole.
Given it was a launching title, they had to stop somewhere and ship the thing. So, like any software with ever, they had to make tradeoffs.
And, well, here we are talking passionately about this game 26 years after. For me it’s an amazing proof that they made amazing tradeoffs.
Because, yes, we now have plenty of time to analyse the thing and find issues with the game. But, the 6yo me, the player me, they have nothing to criticize about this game.
For me it is still a perfect masterpiece given its era and technical context. I don’t think the game could have been really better than it is without breaking something and I’m pretty sure that the engineers at Nintendo considered the game as « finished » and liked the result themselves. It shows in the game. The better would have been the enemy of the good.
But in the meantime you are also right because Mario 64 DS was a really good extension. I miss this game, it really deserve to have its remake. But this version hugely benefited from the evolution of the Mario universe and the technical superiority of the DS so I’m not even sure it could have been done in the 90’s.
I hope we’ll today be able to play a newer version of this game. Be it official or not, I crave for SM64DS with the original controls.