3D requires orientation alot of modern humans dont have that.
Going from left to right is also kind of hand holding and since modern humans also have a problem with thinking for themselves that is what they prefer.
2D is the classic experience. People that like to play Mario but dont understand 3D go for 2D.
I also believe that if Mario64-2 would be called "Super Mario Bros. 3D" it would sell more copies simply because of the name.








