Now, I'm sure someone will argue that MMOs aren't about these things. They are all about PvP, community and teamwork. Right. Any good team-based online shooter does these things far better, provided that you play with a clan and compete in ladders. You can claim that planning and executing a huge raid requires tons of teamwork, but planning and executing a victory against a human team without the benefits of stats and loot is far more involved.
I played WoW with hundreds of fellow guild members. We took over towns, we played games with the enemy by showing up in one location and poping up in another to kill their NPC hero/leader, and we had lots of fun doing it. That takes a ton of coordination and planning. There's nothing like the feeling of rolling through town with nothing to stop you and suddenly being overrun because the entire server has been alerted you your presence. And on a PvP server, there's nothing like the danger of being attacked out of nowhere at almost any time. That's why I played that game. Single player games and shoebox shooters are not the same thing.