This has been part of combat sports (not just MMA, but boxing, wrestling, etc...) for ages. The only division you generally don't see this in is heavyweight, since it generally doesn't matter (except for the few that need to make 265). I agree it's kind of silly, but that's how it is. There has been talk aboutgoing with weigh ins right before the fight so that the fight you weigh in at is the weight you fight at. All that would do basically is move almost everyone up a division or two.