Most Helpful Girl
I can't say for everyone, but for me it's to avoid saying something I regret in the heat of the moment. I don't want to hurt other people since I know when I'm mad everything seems worse or more serious than it actually is. For me, I know that I have a bad but fast temper. It takes a lot to make me mad, but if I do get mad it's really really bad. However, if I take 5-10 minutes to calm down, I'm able to move past it enough to talk rationally about whatever it is that bothered me.
The other side of it, which I doubt is universal, is that I can't handle being yelled at, especially by guys. I know that men stronger than me and could hurt me if they wanted to and the only reason they don't hurt me is because they don't want to. When a guy's mad I have no way to know if he's suddenly going to hurt me, especially if I'm alone with him, so I really don't want to provoke anyone. Also, I really don't know how much control guys have when they get angry because of testosterone. Most of the guys I know, even ones who are normally level headed, have punched holes in walls against their better judgement when they were angry. On the other hand, not even my angriest female friends get violent when they're mad (they do get verbally abusive, and I also don't handle that well, but that's different). I've been in an abusive relationship before though, so I read into even slight behavior patterns a lot and go to ridiculous lengths to avoid being in that situation again.