I searched a little if this subject had been discussed before but forgive me if I am wrong. I think that it would be great if there was a private message (PM) button on a users profile because people may want to discuss private matter with their friend. If this was introduced I don't think there should be AP for it because mods and admins would not be allowed to see the message because it is private and people may just write spam and it would be abused. I hope you consider my idea.
P.S forgive me if someone else had this idea before me.
Tried to find the thread with it, but it is probably located somewhere in the Ag3 section, so you might be able to find it yourself. Either way, duplicately answered.