On the topic of omnisexuality - i do like the larian approach of romance being written with everyone in mind (like in DOS2). I also think the critique of characters being a bit too pushy is valid and making the overall immersion worse as a result is valid as well.
I actually like NPC's initiative on flirting, its one of the things that makes them look realistic. I don't mind if they are even abusive with dominatrix intentions. I don't understand the people who think that the player should always be the initiator of romance
It would be fine in moderation. Not when they try to jump your bones after knowing you for 3 hours. Save it for Act 2.
Some characters it's fine I guess, like Asterion. Because he comes off as a kind of a creep when you meet him anyway. He is essentially the same character as Zevran from DA:O, who was also a horny weirdo.
I think the solution is a disposition meter. Flirty dialogs should only be "unlocked" at a certain level. If your level is too low and you initiate a flirty dialog, your followers should get mad and drop the meter even further.