For me an MMO is not something to be played alone.
(I have played WoW for a total subscription time of a little over two years. I raided in Burning Crusade, and I raided in Wrath of the Lich King, dabbled in Arena, played battlegrounds for fun, etc. I will probably return sometime in the new year, as I have many friends that are doing the same.)
I really don't like WoW. On it's own, WoW is a pretty boring game. There is some fun to be had with the quests (which get old pretty fast), there is some fun to be had running dungeons. But once you've done one "pass" of the game, and tried a little bit of everything, the rest may feel repetitive.
For me, from the moment I started a level 1 character (a dwarf priest), I was thinking about raiding. I liked the idea. I liked the sound of having to work as part of a team to overcome obstacles that were otherwise impassable (and get phat loot that you could show off to your friends as a reward).
Once I finally got to into a raiding guild, I found out what the reality of the situation is. You see, most guilds arn't very good. And by "very good" I mean, most guilds take months to clear a new raid, not a few weeks.
Because trying a new boss is fun. You gotta make sure that every player is 1)playing their character properly - so dpsing healing or tanking 2)players are playing the encounter/tactic properly.
1)is learning the game 2)is following instructions. People seem to be SO BAD at 2), that in 100 wipes, there are people still dying to the same, predictable, avoidable, obvious effect. (lava waves on sarth+3 -- no, really, on the kill we had 1 person die on the FIRST WAVE, but lucky he was the only casualty)
Dragging players kicking and screaming into a fresh boss kill feels good. After each kill and as the weeks go by you can actually notice people learning the fights, the fights get easier, people know what to expect. Then you try hard modes, and have to experience this whole "guild learning curve" effect all over again.
I enjoy this, but I hate this.
I enjoy getting better, teaching, helping, contributing, and actually PERFORMING well. I feel good when I didn't make any mistakes, when I tried my hardest. I feel frustrated when the reason we failed was because others were not doing the same.
But after the wiping is over, after the drama on vent, I enjoy laughing about it with a few guild-mates. Who, like me, enjoy playing well, but understand that in a guild like ours patience is a virtue.
TLDR; I hate WoW because of the players I have to play with, I love WoW because of the players I CHOOSE to play with.