It's harder to control yourself in a 3D Mario game in that if you're hit by fire, whether it's a fireball or lava, your posterior makes you run uncontrollably. In a 2D Mario, there's no function for posterior burning. That and the fact that Super Mario 64 has enemies that try to push you from platforms and instant killing via Lava would be cheap and problematic.
Pixel Art can be fun.







