I don't really care about them, to be honest. I wouldn't mind if they disappeared altogether because now that I think about it, the moment the number of posts in the forums started decreasing is also around the time that usernotes came about...

EDIT: It turns out this is a filthy lie, they started in 2004 and the posts per day decrease came about in 2006. But I still prefer PMs and posts to usernotes.