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. I don't really see the point of influencing a character's sexuality though: that's not really any different to the playersexual stuff we have already. I'm slightly on the fence about the subject; using DA as an example, I preferred Inquisition to DA2 but I suspect I would've had a very different opinion if the only characters I liked were unavailable because it wasn't a thing.
I hated Sera and it had nothing to do with romancing her, haha. I just find her obnoxious.
On the topic of Inquisition - I agree with people who say romance was handled better there, as much as I dislike DA:I. But let's move for a moment from the playersexuality discussion and consider another reason the romance system was better in that game.
It's that the characters don't push themselves on the player. You can be friends (or generally on good terms) with all of them WITHOUT them humping the PC's leg. Romance is player-initiated and clearly marked (a heart icon on the damn dialogue wheel). No accidental flirting, no pushy companions. My female Inquisitor could be friends with Sera (yeah, I hated her, but I wanted to see her quests) with no problem. It should be the same in BG3. Someone wants romance? Go for it. Someone hates romance? It's not pushed. Someone only wants to romance one specific companion and be friends with another? Also possible.
The current system also makes every companion universally slutty. Sex bots, as others said. Pushy ones. It would be reasonable to have Astarion flirty, and maybe (unfortunately) Lae'zel, but the rest? Really? All of them? Now it's the choice between playing with an all-slutty party and playing with a custom party.
It's especially bad that BG is largely about companionship and camaraderie - something Larian frequently noted themselves. And now the companion/party aspect looks like a cross between high school drama, soap opera and half-assed dating sim with extra porn. No camaraderie to be had when every companion is primarily concerned with how to bang everyone else.
Lowkey, the party banter being for the most part them all flirting with one another was way more cringey to me than the romance stuff. Pretty sure the only ones who have none of that going on between eachother are Lae'zel and SH.