Until someone can ask one of the folks in charge of handling the port, we can only speculate and keep speculating.
I myself came to the conclusion that the team handling the transfer to the Xbox got to work with outdated assets.
What makes this most apparent are some of the music tracks that sound different. It is striking how these are closer to the music demos produced before they got converted into sample based DC audio, hinting at files of an earlier point in production.
I also guess that some of the objects had to go or needed changes because of the stencil shadows that are not just cast by characters but pretty much the entire world's geometry. Looking through the changes, there are a bunch of examples where transparencies were removed. I guess there were some issues with shadows with those.