Um, the same exact thing? You don't have to look that hard to see the story behind World of Warcraft. The only difference is that the story is incredibly open ended as compared to the completely linear Final Fantasy. The lore behind it is almost as good as an excellent book.
Aside from the above, the thing that draws me to the game is the strategy behind each raid encounter and the difficulty in successfully applying that strategy in order to make it work. You have 24 other people that you must rely on in order to get things done and, more often than not, if one or two people mess up, the entire thing is going to end horribly. Also interacting with a different assortment of people is fairly enjoyable.
I don't so much enjoy the leveling portion of it, but sometimes it can be very fun. The first time through, on my mage, I missed a lot of stuff. A lot. Going through on my druid I am finding a bunch of goodies that I never picked up on.
Also killing retarded people or watching retarded people get killed. That is fun too. Nothing like seeing an idiot horde gank you in the middle of town only to get his ass handed to him several times by surrounding alliance/town guards. Idiots.
I do not understand how people can get addicted to anything, much less World of Warcraft. Sure, it is a very enjoyable game and it helps pass the time, but to become so enamored with it that you stop doing anything else in your life? That is just silly. I spend a great deal of my time playing the game, sure, but I still have a full-time job and a very successful relationship, it isn't that hard to balance all three. I guess some people are just too stupid to get that.