Ok, while the Lich King plot and new Death Knight class really got me interested in buying WotLK when they first announced it, the idea of siege warfare is what got me excited for sure.
Ok, granted, siege warfare might not have turned out the way everyone thought it was; demolishers destroying towns and villages as shown in the video wasn't implemented, and the aerial dogfight they advertised didn't happen either, so essentially the only siege warfare was against castle gates and the walls of Wintergrasp, but at least we got to actually destroying some things, even if they were walls and gates. Hey, Cata even gave us some towers in Top Barad to bring down (yes, even if they're just towers).
So why is everyone so unhappy with siege weapons? I can't ever play a single Isle of Conquest or Strand of the Ancients map without people complaining about how stupid singing is, and the only people who show up to play at Wintergrasp are the people I bring from my guild or invite over trade chat.