Oct 23rd 2010 5:46AM @RogueJedi86: I didn't say that WotLK is like a battle chest -- that's what the battle chest with Vanilla and Burning Crusade (and assumably soon Wrath of the Lich King too) is for.
In the meantime, the WotLK DVD is the "one disc install," though the battle chest may (I don't have it, so I don't know) not have this feature on its own.
Oct 23rd 2010 12:09AM @Matt: First of all, they already have battle chests that reduce the cost aspect substantially. Secondly, the WotLK DVD (so assumably the Cataclysm one as well) does a one disc install! Seriously! They should have made this more clear, yes, but you can install everything you need minus patches from the single DVD.