Nowadays, says Tobold, things just aren't the same-- if you're just coming on board, you might wonder where all the nine million players in this game are (answer: Outland). And with every expansion, the real action will get farther and farther away from the starting zones-- would you come to this game when WotLK releases if you knew that you had 80 levels and two expansions to get through before you joined the rest of the world?
There are probably benefits to coming late to the party as well-- nowadays, we have guides aplenty, and you don't have to suffer through any of the old bugs or balance problems that have already been fixed. And if you're looking for single-player content, there's plenty to go through. But joining up with the other 10 million players now isn't nearly the same experience that everyone had a few years ago.