Being the devils advocate here but:
Then all the females having enormous boobs and wearing nothing means.......The lack of "obvious" gay npcs means Blizzard aren't adding any stereotypes just to be "correct". That is a good thing.
I do have to say though guys, that quest "The Day Deathwing Came" or something, when you are told the orcs story and you get to ride a motorbike with a "hot babe" you can choose to take a guy with you I think that counts a little bit. Good on ya Blizz.