MMOs are a strange beast. They are designed to make you play as much as possible, yet addictiveness does not always equal fun. In the field of pyschology, there are several kinds of rewards systems, and the one that seems to be the most successful is the random reward introduced at a random time. Sometimes you click the button, and nothing happens. Sometimes you click and get the food pellet. It's this mechanism that fuels the slots in Vegas, and when you walk away empty, as is statistically inevitable over a long enough stretch of time, you tell yourself that the overall value was the experience itself, since you come away with nothing tangible. MMOs take away your time and they never deliver a discreet conclusion.

I played a ton of Dark Age of Camelot shortly after it launched, and I find myself reminded of it negatively every day that I play World of Warcraft. To discuss the differences in favor of WoW would be an article in itself, but I'll try to keep to the main points.