Indeed. For a number of players the concern was that making every character bisexual served to erase gay characters and precluded stories like Dorian's.
I haven't played with Dorian in my group yet, but I am playing with Sera, and I haven't seen a single piece of dialog or anything, really, to indicate that she's gay.
I have done Dorian's quest, which obviously wouldn't work with the "player-sexual" idea, but what would change if the game only offered that quest after the male player began a romance with him? Is his sexual orientation intrinsic to his character? I always assumed that would be more insulting than the opposite; that your sexual orientation does make you different in some way would be more offensive than it not "mattering" to who you are. Especially in a world where it is largely accepted and the hardships one might face for being homosexual seem rare (e.g. our hardships can definitely mold who we are, but if there are no hardships...).
What would the repercussions be if the player could choose a sexual orientation at character creation, and then the game tailored itself to that orientation? You could leave it in a "default" state should the player not want to make the choice.
Imagine Inquisition as it is now, with the "default" state being that Dorian and Sara are gay, Cassandra and Cullen are straight, etc., but the player gets to choose their sexual orientation. If they choose gay, then Cassandra and Cullen become romanceable by the same sex, and if they choose straight, then Dorian and Sera become romanceable by the opposite sex. The respective quests/content would be disabled/altered in some way. Essentially, the idea would be to make the player as much of the "Dungeon Master" as possible, with the ability to tailor the game the way they see fit.
I mean, as someone else pointed out earlier, Cassandra is, essentially, the "story romance," like Liara was. She gets more attention than anyone else, because it just makes more sense. She's there from the beginning. She's a companion. She's part of your war council. If there was a default story, if this was a movie or a novel, she would be the love interest because it just fits more. So it's kind of unfair, then, that homosexuals can't have that narrative synergy. Again, the ability to be the "Dungeon Master" could be valuable. I think we all know that if mods existed for this game, some of the first and some of the most popular would be the "Cullen Is Gay" and the "Sera Is Straight" mods.
Would being able to choose your sexual orientation at character creation be offensive in some way? I'm honestly blind to these things. Or is it, at least right now, just too much work to make the game be so malleable in this way?