I recently bought Morrowind GOTY edition, and remembered this project, and decided to set it up after getting frustrated with the combat system in Morrowind. I read in the requirements that Shivering Isles was needed. I just have Vanilla Oblivion without the expansion packs. What problems would occur if I were to set up Morroblivion without Shivering Isles?
I think that shivering isles
I think that shivering isles is needed for some resource(meshes and textures). Not having them can cause graphical errors or CTD

Missing meshes, missing
Missing meshes, missing textures, script failures at least.
Believe me, SI is required for a reason.