Ultima Online, on the other hand, was such an expansive and interactive world. You didn't choose your interactions based on personal preference. There was always the threat of another real life player coming to kill you, which created a sort of camaraderie in hunting grounds. You may not know someone, but suddenly he'd come to your rush if a murderer approached, and if you were lucky you both ended up outnumbering the murderer and you'd walk away with his loot. You wouldn't even know the person but you'd end up sharing an intense experience together where the stakes were high (if you died, you lost EVERYTHING). So many friendships were made that way.
It was a different experience that was about more than levels and raiding groups and elite loot. It was a true social space where your actions affected other players experiences, for better or worse. To me, this is the soul of the MMO, and exactly what WoW lacks.