raiding is an integral part of WoW's design. A lot of people think that's a bad thing. They'll say raiding is only for the elite hardcore, and that it alienates everyone else. Here's a shocker; Damion Schubert -- a renown MMO designer whose games have historically been pretty much the opposite of raider-friendly -- is not one of those naysayers.
He recently updated his blog with a strong defense of Blizzard's decision to emphasize raiding. You should read it for yourself, but the gist of it is that there are more raiders than you think, that players of a PvE game want a PvE endgame (as opposed to a PvP one like the Battlegrounds), and that because raids are re-playable content, Blizzard gets more bang for its development buck.
His ultimate point, though, is that Blizzard focuses on raiding content because that's what players want. But I wonder if a lot of those players, especially the more casual types, would want something different if they were aware of other options. And Schubert suggested that there are alternatives. What are they, and do you want them, or are you perfectly happy with working your way up to Black Temple?