MMO's are NOT for the text book casual gamer (30min to 2hr~ playtime). Even if you can do stuff in-game with that time, at some point the community will have higher demands of you.
MMO casual != console casual. I consider MMO casual 2 - 5 hrs playtime, generally (depends on weekday & weekend player habits), but that's me.

Yoshida seems to be for: weekends = hardcore & weekdays = casual. There's no doubt that there will be higher demand content at some point. Because of this, the community will place demands on players & those who can not meet them will be excluded or won't progress nearly as fast (these people will complain).

These days though, all games are being dumbed down to the casual level, so who knows. Soon we'll be seeing fart jokes in-game.