These medium-level players are not really hungry for the new features that Wrath of the Lich King brings. It's really about satisfying the players who have reached max level, whether they solo or whether they PvP, whether they raid or role-play.
If they're at max level they're all saying, 'I want more, what are you guys doing for us?'
On the Big Bad...
Kaplan: We're giving all players going into the expansion interaction with Arthas. We were too protective of Illidan [the arch villain in The Burning Crusade] making sure we didn't waste the opportunity, so now you're interacting with him straight away.
You're talking to him, having these moments with him, so you don't have to be a raider to see him. We're also having a Caverns of Time mission - The Culling from Warcraft III - so that you can go back and play alongside Arthas when he was shiny and good, when you're burning Stratholme.