I was recently listening to episode 7 of No Prisoners, No Mercy, and the hosts talked about the difficulties in making a pickup group for Karazhan and the attitudes of players that made the group fall apart. The hosts asked players who have visited Hyjal to comment, so here it is. I was initially planning on posting this as a comment on the episode page itself, but I felt that my reply was long enough to warrant a separate post.
Basically, there's two basic ways of arranging content in a game. Horizontal means that you have a lot of variety, but little progression. Vertical is the opposite. Levels are vertical. You need to reach level 2 before you can reach level 3, and most of the raid content in WoW is vertical. You won't have a snowball's chance in Hell to get anything done in Hyjal if you don't have high-end Karazhan/Serpentshrine Cavern/Tempest Keep quality gear, and the knowledge and skills to match. Conversely, the pre-raid PvE dungeons in WoW are mostly horizontal content. Dire Maul was about as hard as Scholomance, and Shadow Labyrinth is about as hard as Arcatraz or Shattered Halls.
In my opinion, games need to have both, and maintaining a balance is one of the factors that makes game design hard. Variety is always good, but there also needs to be the next challenge in the horizon. As your knowledge, gear and skills improve, content that kept you at the edge of your seat before becomes trivial and boring. At that point it doesn't matter whether you're killing elves or demons or orcs if they all die within seconds. Likewise, if you know by heart that every enemy orc does X, Y and Z in that order, doing A, B and C to counter those moves becomes second nature and killing orcs becomes boring, even if doing A, B and C was appropriately challenging for you.
Arguably, Blizzard is vastly more focused on vertical content than horizontal, which is not that surprising considering that their lead game designers are former Everquest raiders, and they're making a game that they themselves like to play. Illidan's often-quoted one-liner "You are not prepared!" actually describes WoW pretty well. :-) Both the players and the designers know this, and expect everyone else to know this as well. And that's why people were concerned about raid composition, gear and experience (read: knowledge) in that Karazhan raid. Karazhan is not designed to be the starting point of the endgame PvE experience, the non-heroic instances are. I admit that I would also have concerns about a 600 spell damage warlock making a Karazhan group, because you can go much higher with nonheroic and heroic gear before even stepping into Karazhan. Especially if I don't know the player. Skill and knowledge are harder to measure than gear, and you can't always compensate one with one of the others, especially if there's a "gear check" encounter (like Curator) that you have to complete. The vertical progression in WoW goes so far that in some encounters your raid literally has to function like a well-oiled machine in order to succeed. And that is exactly what players wanted.
But what's wrong about giving players what they have been asking since Molten Core? That not everyone wanted it. Some people liked the less-demanding MC raids where you could chat, goof off and generally have fun with 39 of your friends. I have a good enough view from my ivory tower to see how that could be fun. My playstyle is not the One True playstyle for everyone. In my opinion, one of the major factors that made WoW the market leader was that it catered to different playstyles. That allowed Blizzard to get the most out of the network effect. If Blizzard undoes their good decisions and allows the balance to be swung too far in one direction (no matter what that direction may be), then they do deserve to lose market share. And Warhammer may be the game that all of those disillusioned players start playing. And that's good. Complacency kills, and even if I never end up playing WAR, the competition will help keep both Blizzard and Mythic on their toes, resulting in both games improving and thus benefiting fans of both games.