That might be the reason many have a fondness to TBC that has depleted since. My friends list was put to heaviest use in TBC, and had some use in WotLK. I'm not sure I've used it much beyond tracking RL friends outside my guild on Cata. It seems to me that implimentations like LFD/FLR have turned out to be one of those "be careful what you wish for" kind of things. While it is nice to queue to play anything whenever you want, it really went to far in that there is no reason to form "working relationships" with anyone, even your own guild. In fact, for guilds that formed around social aspect rather than skill aspects those tools are often prefferable to guild-runs where you might have to teach someone the ropes of a dungeon they have not done before whereas pugs have a higher success rate especially considering the "vote to kick" those expendible, underperforming players.