Hmm interesting topic. I figure I'll drop my 2 cp in on the whole deal.
I started playing AD&D when I was about 12. Did it off and on for years, but it wasn't until I hit university that I started playing it consistently. Thing was, in those early years of university, I had a lot of friends who were into D&D type-stuff (Magic the Gathering, computer games, comics, etc.), but most of the guys had given up AD&D a year or so before I met them (they were basically all friends of friends before). I pretty much just played AD&D with three of them, while some of the others played Call of Cthulhu and couldn't be talked into playing anything else. Even the friends I did play with tended to heavily modify the rules.
Then 3 ed. hit and all of a sudden pretty much every friend I had was into the game again and we even made some new friends who were getting into D&D for the first time. This is known as the "D&D Renaissance" amongst some of my friends. It was great, and still is the best D&D time of my life.
A year after 3 ed came out, I started playing EQ. I soon discovered why it is called "Evercrack" by many. I was basically coming home from work, shutting myself up in my computer room and playing until I went to bed (often rather late). I was ignoring my roommates, not getting enough sleep and was ignoring my D&D campaign I was supposed to be running. Now, I'm not trying to decry EQ as evil; I actually met a friend on there who I started chatting with through IM programs too. She's still a good friend of mine, even though I've thoroughly given up on EQ. But, as Henry our August Mod pointed out, it has a tendency to emphasise a very detached type of relationship, while not allowing a lot of time to build real-world relationships. This has happed to others in our gaming group, who have snubbed D&D sessions for EQ and other computer games. Really, it's up to the strength of will of the person playing to choose not to spend a lot of time on those games (I am weak, I admit), but the fact you pay for them monthly (and not cheaply either) makes you feel like you have to play a lot to get your money's worth. I'm not saying MMORPGs are evil, but they can be deceptively immersive.
Like I said, I've given up on EQ, and rediscovered how much I enjoy the social component of D&D. There's a reason I call my gaming buddies friends; they're a genuinely cool group of people to be around. Yes, D&D does have more game-related advantages over CRPGs (I've never played a computer game that featured such unlimited potential for enjoyment as D&D), but I think its real advantage is, as Henry said, it's social component.
I'll be playing D&D for the rest of my life, but I doubt I'll get back into EQ. I just love my friends too much to turn my back on them and glue my face to a computer screen again.
(Sorry for the length too, I guess I had a lot to say on this topic...like I said, it's very interesting!)
edited for clarity...and spelling