Ok, now with all that history out of the way, I’ll try and jump into the guts of why it is I like MMOs so much and why they are the games I find myself playing and wanting to play.
Probably the best reason is because of my experience playing with Sally in WoW. The built-in support of grouping in MMOs makes them such a great activity for couples. Very few other games allow the two of us to have separate but complementary roles together. We always have a questing buddy, a group of two is more resistant to ganking, and you always know at least one of the people in a larger group is someone you know and trust. Very few other types of games have such a rich set of tools or variety of actions that a duo can engage in.
That social/group aspect that we have together is appealing in general. The existence of shared goals and needs for grouping are something that I find I miss in single player games now. Unless a single player game has a very good story that keeps me interested in the world, I’d almost always rather be playing a game that has other people in it, especially if I can work with those people in a group.
The constant character advancement is also seductive and a well known mechanic in MMOs. Getting that next piece of armor or making a little more money to afford the new item is an obviously powerful incentive system that I buy into wholeheartedly. Sure, I could play Crysis for a while and it’ll be fun, but it has no longer term implications. Every action in an MMO, however, is part of the larger story which I get caught up in. Running missions in EVE in isolation isn’t as fun as playing Crysis. But the mission running is part of a larger story: I’m both making money and gaining standings so that I might possibly be able to set up my own station, afford better ships for PVP, or play the market on a larger scale. In addition, I might be running those missions with people from my corp or at the very least, talking with other folks who are playing the game about what we’re doing.
There are certainly non-MMO games that capture my attention now and again (Rock Band being the primary one these days), most games just don’t have enough to grab my attention for very long. Add the same reasons for Sally as well, and you get a double whammy that doesn’t have us playing many non-MMOs either together or apart.
Be nice. Keep it clean. Stay on topic. No spam.
You can use these tags:
<a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>

Design adpated from Upstart Blogger Minim by Upstart Blogger.
I think, too, part of the appeal as you were kind of saying is the sense of being part of something larger culturally. It’s not just that you are helping achieve a larger goal in EVE or WoW, it’s that so many people share an understanding of what those goals mean. And, these things are cultural phenominoms in their own right, save for the big name games that make a huge splash (Portal comes to mind) there’s something about playing MMOs that connects you to a much larger cultural sense of event and belonging. Playing EVE, or WoW isn’t just about the in-game rewards it’s about the forums, the blogs, it’s belonging to a sub-culture that doesn’t exist with the same solidarity and sense-of-self with single player games, or even online multiplayer like Halo etc.
The main thing about MMOs that I think make them so addictive is the constant trickle of minor goals (finishing a mission, beating a tough NPC, what have you) with the occasional “big” accomplishment. It’s the persistent little shots of endorphins that I think make MMOs so easy to get hooked on.