The Alliance have the right to be angry at anything they want to be angry at. Doesn't mean they're justified. I mean this. The Alliance have been wanting to storm the gates of Orgrimmar for a goddamn decade, and when they finally get it they're pissed because the Horde has to do it too? Believe it or not there are many on the Horde who don't want to storm the gates of Orgrimmar, period. For them this entire patch is like being forced to eat a giant bag of lemons, peels and all.
So keep that in mind.