Why not? I agree because it is very fine to know who you need to remove what you already said.I think that it would be nice if you could separate your friends on the server in active members and less active / inactive members. So, if you want to add a friend, but your friend list is full, you do now have a better overview of people who are less active and this might help you to make a better choice in which person you're going to remove from your friend list. It's not a crucial feature, but it would be pretty handy in my opinion!
Maybe it will be based according to playtime for the last X (week, day, etc.) or the last time thye logged on.I like this idea but how would they separate less active to active friends? (or do you just separate them your self?)