That said, it comes down to a simple question of mathematics. There is no loyalty or ethics involved, yes it would be nice if there was but that is not how ATVI operates. It boils down to what is the most profitable thing to do. You may be right that a small fraction of players actually will not buy MoP in protest of the release date. But far more revenue would be lost by not getting those extra few months of paid gametime from the APers. Throw in the fact that holiday is traditionally the best season for video game sales and it just makes too much sense to not release it then.
I would expect to see some sort of pre-order/Annual Pass combo deal be announced for release sometime in Q3, because there is really nothing else going on to boost subs for that quarter.