Absolutely, if instead of all this there were more good romantic interactions between you and your LI, the game would probably be a masterpiece.
100% this. They did it at least once with Gale. When you save the boy from the harpies, he tells you a story about his boyhood shenanigans. This is a GREAT moment because you get to connect with him im a way that isn't related to the tadpoles, the weave, or Mystra. And it osn't necesarily romantic, but if you go that route it really adds to his romance imho. It's a very genuine, charming moment. Especially since you can kind of tease him with a dialogue option that is akin to "Yea I can imagine you being a handful as a boy."
If there were more little things like this, it would make the sex scenes much more impactful because you are building a bond with the characters on a deeper, more human level.
As a Halsin romancer, I keep thinking about how we could have had little interactions like this with Halsin in Acts 1 and 2 rather than getting the big old info dump we get after the Thaniel quest. The plot changes and cut content for Act 2 as we are discussing it in his other thread certainly dont help things in this regard. Not only would this give him a little more to do, it would add to the slow burn and longing that I was feeling for him.
The problem with Halsin specifically, in my opinion, is that it is too actively imposed, you could say that it is simply pushed through and "advertised" to the player, without paying attention to whether the player wants it or not. I don't think Halsin's fans would be too upset if Halsin only paid attention to them and not everyone else. Besides, he's also encroaching not only on you, but also on the person most dear to you - your LI. The very dialog with Halsin, when he proposes a relationship, is constructed in a rather disrespectful way towards your LI. You can't even say that you love the other person and are faithful to them without any ambiguity. As a result, the character is hated by a certain part of the audience, while he himself, in fact, does nothing wrong if you immediately reject him, simply because of his behavior. The game should consider all players, not just "thirsty", fanfiction and ahem...discord posters.
This just makes me sad, because all of this bleeds into his own romance as well.