Yeah, but that won't happen. Imagine pissed hetero part of Astarion's fanclub if he was only gay. All those pretty drowish girls wasted.
You just wrote this, and I'm already furious.
Also, this is a stupid idea. You suggest making characters represent LGBT community (or represent someone like heterosexual idc), which was enough for me in Bioware games. At this moment, each of us can decide who is who. Representation will ruin everything and only infuriate people, as it did with Jaal from Mass Effect. They made him heterosexual, and as a female player, I think that was unfair to those who wanted an alien boyfriend. But then bioware changed that (cuz ppl cry), and it only made it worse, now two sides were angry. Imagine that someone changes orientation of your favorite character with a patch. And Jaal had these hints in LI quests that his family needed a "continuation of the family". People can be sensitive to this. If they had initially made it bisexual, both sides would have been happy.
Similarly, Dorian in Dragon Age had hints that his family was angry because he couldn't ‘continue the family’, and he's gay LUL. Do you understand? You're not just asking to make a character gay (or other), you're asking for representation. And this is rlyyy bad.
That's why making everyone bisexual (conditionally) is much better. Everyone has their own canon. There is no representation. Enjoy it and don't interfere with others. This is best way.