Wouldn't Obito be such a badass if he had both of his sharingan's? He has his right eye's kamui, which apparently let's him teleport or well take an object he touches or himself into a different dimension, and with his left eye(kakashi's eye) he can actually kamui whatever he pleases.. It's something like Sasuke's Amaterasu where in one eye he casts it and the other has a different purpose which is to manipulate it. I say if Obito had both his sharingan eye's he'd be a badass. (Not to say he already isn't though)