I beg to differ, World of Warcraft is some of the most fun I've ever had in my life. It was destroyed when they changed the game to have multi-server raids etc. that ended the social aspect of "your server is your world." No longer did you have to make friends and have a life on your server that was as addicting as real life. You just had to queue up and let the computer match you up with people. And then the magic was gone.
Have you played any sandbox games more seriously and joined some guilds etc? I would say WoW was more of a "world" in the start (but not on a comparable level to others) and turned less and less so over time. The one thing blizzard always managed really well however is a crazy level of polish. I am sure they could make any kind of game really shine.
