Why do we assume that we want to, and must be able to, play with friends? That's just asking for trouble. I think it's an unreasonable expectation. I don't do everything with all of my friends. Why should WoW, or any other game, be special?
Ideally I could play with friends, but in my experience the thing preventing that is not skill or server divides, but divergent interests. The friends I did play with were friends I had made through WoW, friends with whom I have common interests: raiding and arguing. I have a few friends I first met in real life who play/played and I wouldn't want to play with them. We don't want to do the same things in the game. It would be as ridiculous as saying "let's play sports together!" and then I want to go running and they want to play football. Or we both run, but at different paces, so someone ends up left behind or dragged along and what fun is that?
It's not necessarily that my real life friends are bad. I mean, maybe they are, or maybe not. I don't know and it doesn't even matter. But when two are RPers, another is bowing down to the cookie-cutter gods, and I'm searching for creative ways to die, it's not really a compatible experience.
I do actually want to play with friends, not the friends that I dragged into a game, but the friends that I met in the game. Those are the friends that I know want to play it and play it as I would. I wonder how much happier people would be finding more friends who share interests rather than trying to push friends into unwanted 'fun'.