Which sometimes makes me wonder why I even bother playing these games, as I could have pretty much the same experience playing single-player RPGs.
Maybe because you can still get people to help you and do things for you without having to socialize too much. I suppose you can always just grind if you get stuck but sometimes its more fun to just have a stronger player give you some assistance. Free items and stuff are cool as well.
And again, I have to stress that even if you don't socialize much just the fact that there are other players there make it more interesting. What's the point of having a strong character if you can't show it off? Not to mention other players have often made me interested in playing characters or builds I may not have tried otherwise. I know I certainly impressed a few people when I was one of the few barbarians on battle net that specialized in throwing weapons and I didn't suck on top of it.