That's because judging from ME3, male and male pairing was so underused by the playerbase. Do you think the majority of the playerbase want them to focus on adding it for what is basically a very small percentage of the player bases desire, when there are other things a bigger majority of the player base would use?
I would love to read your statistics on that.
But that takes us back to the chicken and egg situation. Games that are targeted at the male straight gamer will most likely have the male straight gamer as their key fanbase. As David Gaider has put it so eloquently: "Game companies should stop treating 47% of players as an added bonus".
I kind of dig the man.