They never said it was going to be a light hearted, silly expansion. They emphasized at Blizzcon that it was going to be about putting the WAR back in Warcraft. That's not even going into how they've been quite clear from the start that negative emotions cause a physical manifestation and that the invasion is going to cause lots of those. I think you're mixing up all the LOLKUNGFUPANDALOL reaction with what Blizz actually said.