Fencer: Why? Well, I came (and still am for another year) to BK because I wanted to play turn based games. I want to play lots of them. Smoothly. With as little hassle as possible. I don't care about photo albums. (If I want to share pictures, I use my own photo album, or use Flickr). I don't collect friends (if I wanted that, I'd go to Facebook). I don't have the urge to scribble on walls. Or use yet another chat room (jabber at work and a couple of IRC channels is more than enough). Google gives me more than enough links; why would I turn to a turned based game site to collect links? Achievements? I don't need them.
I realize that for others these are cool things. But I'd happily give up the achievements, the walls, the photo albums, and the chat room for, say, differently marked racing and non-racing checkers. Or for the option to have the computer do meaningless things for me, like moving in a game when there's no choice to be made.
I don't plan to leave at the moment, but if I would stumble upon another good site and I were to make a choice between BK and a new site, the games, the interface, the other players and the price of the membership would be factors for me. Photo albums, walls, chat rooms, etc. won't. Similar when it comes to membership renewal.