Well, this is actually a very good question to ask, as I myself also have come across this feature more than a thousand times, and like the op, I have actually added alot of users to my buddy list, even the admin of this forum, including the campaign managers and so many others, but then, never really saw any difference or the effect this has on the profiles I've added as a buddy to my list.
This is something I once wanted to ask but I got occupied with something else and that was how I completely forgot to ask the question.
Would be nice if we would get a reply of the admin on this thread, I possibly would assume this feature is still under construction at the moment, and in the future, there will be a way by which posts or comments from users in our buddy list are given special place in our individual accounts or profile, but this can only be confirmed or clarified by the admin himself.