It would definitely be a game changer.  On the one hand, I kind of like the idea.  On the other hand, 2 words: griefer ramming.  As it stands now, about the only thing a griefer can attempt to do is get you to killshoot yourself.  This would open up a whole nother level of dweebery.  Probably a good portion of the reason it's not on right now.
Wiley.