You're such a cynic, dude.
At the moment, the benefits have to do with privacy. There's a new option called "Profile Privacy" which allows you to block certain elements of your profile from people who aren't on your friends list, if you like. Naturally everything is public by default.
Other than that, it's just a way to keep track of some people a little easier than others, which admittedly matters less on moderately-sized boards, but matters a great deal as boards get larger and more active (which we have, over the last few months). I think there might be an option to send mass PMs to your buddy list, and things of that nature, as well.
Beyond that, I have a handful of ideas designed to extend the functionality of all this, such as receiving updates on friends, and maybe some kind of notification system when a friend posts a review/thread/whatever. And perhaps a way to more easily identify them on the Who's Online page, etc.
There are a lot of other things that need to be done first, but eventually I see this as a) a way of organizing certain people as the board gets busier, and, relatedly, b) letting people get more of the updates, and fewer of the ones they don't.