Aside from being a great way to enter a room, breaking down a door can save a life. Can you imagine a friend who entered every room by kicking down the door? On one side of things, very cool. On the other side, replacing a door is a bitch. It's something you have to do at rented offices only. Some place where you didn't put a deposit in.
One of the main rules is not to use a jump kick. That's really unfortunate. If using a jump kick was an option I could break down doors in style. I know several jump kicks, most of them are visibly useless to breaking down a door. My expert axe kick? Not going to do anything except maybe pop the door handle off. At least I could lock people INTO a room.