Kicking someone while they're down is fine if you ask me. It's mixed-martial arts but it's as close to a real fight as possible. Headbutts, I was glad when they took those away because it doesn't take much skill if you're a wrestler to take someone down, let them trap your arms and you can still just slam your head on top of theirs. It takes skill to kick someone in the head on the ground because, well, you have to get them there first. Secondly if it's ok to kick them in the head standing up, I don't see the difference if they're on the ground. You put that person there, or they ended up there because they made a mistake. Either way, it's a strike and you're out to try and finish the fight at all times so if you got a guy grounded in front of you, punt his head into the fourth row and go home a richer man.