Ill tell ya what, half the problem is the textures are low resolution, the other half is that lots of them are simply drawn like crap. I dont have an Xbox version to investigate but im willin to bet its the same thing for them. Some of them they didnt even bother to paint within the lines let alone optimize. Tons of textures have the wrong size specular maps attached to them, partially visible "zone" textures from the old lighting scheme. Its all taking the same processing power, its just MS paint level quality.
This game could get an overhaul simply by finding someone who knows how to use photoshop correctly. If Xbox doesnt get something graphic wise ill post up textures for people to laugh at.