Not stirring up anything. If I wanted to, I'd say something like, "MOP SUCKS AND IS KIDDY POKEMON CRAP" ectectect.
But it's actually quite simple: the vocal minority who hate WoW/Blizzard lost their shit when info about GW2 came out. They automatically placed it as the greatest thing ever, a revolution to the MMORPG genre, and a game that will destroy WoW.
Personally, both MoP and GW2 look interesting. I'll stick with MoP because I played the beta and loved what I saw, but I'll probably pick up GW2 if the appropriate people that I agree with on games like it.