Each of those graphics settings require more bandwidth that the console just doesn't have enough of. For example, texture filtering. For each texture, if you wanted to shoot for sampling with the best approximation in the texture map to obtain a good filter kernel for the particular texture sample, requires 16 texture lookups - way too much rendering time for their graphics engine. I think the big consuming power systems are definitely the physics, destruction and transparency FX. It's just how their engine is designed. They may have been able to extract out more features in the console if their graphics engine was designed around a less accurate physics system, less transparencies, and more opaque surfaces like most games.