>>715668184 (OP)Limited space on the cartridge. At time the meta was to use prerendered backgrounds and play FMVs, even games that had a hybrid 3D system like Xenogears still took advantage of the CD technology. JRPGs were also expected to look really good, be a spectacle during combat, and there was simply no way for the N64 to render those detailed characters with high resolution sharp textures.
It's cool how up until the 7th gen the hardware design guided game design and lead to distinct libraries of games. Nowadays everything is an over the shoulder action adventure/shooter that plays the same and runs on all the current machines.