I like the idea of characters' sexuality being influenced by the players' willingness to pursue them. I'm gonna be a little shit, though, and say it's 2020. People apparentely got into an uproar over female Mandalorian armor. Strong independent lesbian character turning straight because male would attract all kinds of crazies.
I remember a lot of people getting angry because you couldn't do that with e.g. Sera in Inquisition and suspect that was the likely source of a lot of the hate for her, which was often excused as not liking her "stubborn" attitude.
As one of the people who had an intense dislike for Sera; for me it was the personality. It felt like they'd taken internet humour and dropped it into a fantasy setting. It did. Not. Work. The lighting engine making everyone look greasy didn't help; for some reason it really didn't look good on her especially. Anyways, my opinion on BG3: I would personally prefer fade-to-blacks for intimate scenes, and if the characters had specific likes/dislikes with what's between their partner's legs, though I can see it perhaps falling over sometimes. Have specific preferences could be interesting beyond characterising the npcs though; Astarion for example was (I'm assuming) forced to seduce anyone his master took a fancy to. There could be interesting things with that; instead of "let's make the gay character straight" or vice versa, emotional conflict could be mined from it; how much of his attraction to the player character is simply due to Cazador's forcing him, conditioning him to go after that gender as well, and how much is genuine attraction? I think that would cost too much in devtime to do anything with even if I think it's got an interesting 'hook' to it.
Bit rambly there, sorry. I prefer Shadowheart's most right now because she's so... standoffish? She's interested in you, but even now after several full playthroughs, a few partials and yakking away on this forum, if it wasn't for reading somewhere every party member is romanceable, I honestly wouldn't say for sure if she was feeling you out as a potential friend or lover, if not for that kiss at the end of the celebration at camp. I've had lots of fun chatting with her, despite (more likely because of) the little ray of sunshine she is. I really enjoy those moments with all the characters, the ones where you're talking about stuff. When I learned there wouldn't be fade-to-blacks I was rather surprised (not pleasantly or unpleasantly, just surprised).