The issue with WoW in the original WoW and The Burning Crusade wasn't that only a small fraction of the people saw the content, it was that only a small fraction of the people could see the content.  If I wanted to even set foot in the final dungeon, I'd need 24 other players with me, and all 25 of us would have had to have beaten all of the previous dungeons many times (and they're limited to being done once a week) and done a pile of quests to even get into those dungeons.  So I'd literally have to have been max-level for about 4-6 months and playing 20+ hours/week during that time before I could attempt the final dungeon, and then the bosses were so hard that only a few hundred teams could beat them.<p>The solution Blizzard implemented in Wrath of the Lich King (the newest expansion) is to scale the big dungeons (raids) so that 10-man teams and 25-man teams can do them, and also have easy modes and hard modes, so that Ensidia (the best WoW guild) can be challenged by the Hard Mode and the more casual players can struggle against (but ultimately beat) the normal mode.  They also kept adding new ways to get gear, so that people trying to break into raiding on the top level wouldn't have to spend months in the earlier raids, and they were pretty successful at that.<p>You're absolutely right that a more fully developed world with content that not every player would see is very important, but that content's only valuable if it's accessible to all the players.  Anyone can go to the Cow Level in Diablo II, which is what made it great.  But not everyone could kill Illidan or Kiljaedan in WoW, which was why it was a waste of money.