But he isn't defined by that characteristic. It's part of his character, but not the entire thing. That's how it should be. His entire recruitment quest is not about that. In fact, if you imply that he's had a relationship with Felix, he gets annoyed that you would assume that. Most of his banter has nothing to do with that. Hi dialogue in plot-related cut-scenes has nothing to do with that. There is one questline that deals with that. That's it. And it makes perfect sense in the lore given what we know about Tevinter. He's a fully realized, well-written, and well-acted character.
We've had five gay and lesbian companions ever in Bioware games. All of them were romance options and only one of them had a questline that was about his family's views on his sexuality. The other 4 did not. That's a pretty damned good track record and sounds like it's in line with what you want to see.
The problem is that you are asking for a pendulum swing completely in the other direction. Never having that story being told is not any better than only having that story being told. Fortunately, that latter isn't happening. But, it sounds like you want to swing to the former, which I think does a huge disservice to gay players of the game.
See, the thing is, I know it was in line with his culture, but I don't think that was played up enough. I would have liked more talk about how he needed to marry, and that was the issue his father had with him, as opposed to Dorian saying it was about him being gay, since we know that's okay in Tevinter behind closed doors. Then again, that was Dorian's opinion, and we didn't really get to hear his father's.
Also, I know none of the other Bioware characters have a quest like this, but Anders and Zevran both give you the "okay to be gay" talk. And while Bioware may have done this for the first time in a quest, it has been overdone in mainstream media. I personally feel the attention is what does us a disservice, but again, it's just my opinion, I respect why other people feel differently.
For me, I'm so tired of hearing it addressed like it's special. I know Bioware hasn't done it before, and they probably won't do this same quest again, but I've seen that exact story so many times I was tired of it before his quest even started. Again, that's just me. I love Dorian, don't get me wrong, it's his quest I disliked.
(Perhaps to help get where I'm coming from: I also disliked Isabela because her primary character point was her sexuality. I have no idea if she was a popular character, please don't eat me.)