I'm not sure of the politics involved with a rule change. It sounds like a good idea on the surface. They could do yellow cards like Pride or something.
But I don't know how involved the athletic commissions would be with a potential rule change at this point. I know they've struggled to get MMA legalized in states where it wasn't already. I don't know if a rule change would be an easy thing to accomplish or a bureaucratic nightmare.
Thats a good point. Rule changes would be cool, but it might be more of a headache than its worth to try and change them. Especially for an organization as big and established as the UFC.