[Avoiding the 'Wall of Suck']

Game dev Damion Schubert at AGDC summed up the four main factors why people stop playing an MMO, which he termed 'the wall of suck' that a player hits that makes them want to quit playing. I'd have to say he's spot on about all of them... and in my opinion the one that WoW is closest to having is 'The End of Fun', simply because adding more quests and rep grinds does not add anything new that we haven't already been doing for the past 70 levels. I myself am starting to head over to that place where there's nothing that exciting for me to log in to anymore.

He also defined the major types of MMO players:

1. Casual: participates in character creation, does newbie quests and areas
2. Interested: levels 10-20, chatting, battlegrounds
3. Committed: leveling to cap, crafting, grouping
4. Devoted: running instances, 10 man raids, guilds
5. Hardcore : 25+ man raids, rep grinding, competitive PvP

I'd have to say I'm a '4.5' -- I'm not that gung-ho about the bigger raids, but they're fun once in a while.
In my opinion, he shortchanges 'Casual' players a bit... I'd think that most people who call themselves casual players would do more than just play with the character creation and then get bored before even leaving the newbie zone. =P
I think a more fair definition of Casual would be 1 and 2 combined, and that most people overlap each category a bit.

"Next, Schubert argued that the industry uses the term “hardcore” too loosely. He said "hardcore" used to be a good thing because the majority of the market used to be hardcore.
“Now it’s something producers say is bad, and they bring in the grandma test. ‘Why can’t you make it so my grandma play this?’ ‘Boss, I don’t think my grandma will ever like a Babylon 5 game.’”

I think he nails the issue right there... unless your grandma is a gamer to begin with, it doesn't matter what developers do, she won't want to play your game. When my husband explained football to me, for instance, to the point where I actually understood it all, I still didn't become a sports fan. I don't find football interesting in the least, even when it became 'accessible' to me.

It's a waste of effort to try to tailor a game for people who aren't interested in playing games in the first place. 'Casual' gamers are still gamers.