Why SEGA pulled the move they did by making the special stage of the PC version of Sonic 3D Saturn less awesome.
Basically it's the genesis version's sprite of sonic in a half pipe that actually seems longer and easier than the saturn one (not to mention there's no enviorment background).
If the PC could make Sonic R look a little better, I fail to see how implementing the sonic 3d blast special stage would be a hard task to do.