You have good points there.
I myself liked the romance system also, made things more interesting.
I also agree with you points about how some things should be changed, and here are some additions I can think of:
It was at times a bit annoying to just get those pop-up-dialogies, especially when those didn't actually check if the time would be good for such discussion. Once I got such dialogie with Jaheira in the middle of fight
IMO a bit bad situation of talking dreams and relations...
Also, like you said, it was too NPC-oriented. You didn't have much change to affect when and where those discussions came up, you just had to make correct statements when those situations rose up. A bit non-realistic if you ask me. That's why I also liked your idea of being able to purchase things to attract someone.
But in general those romances were interesting, and should be implied to new game also. But some changes must be done, in the way those were in BG2 it won't do. And also, in BG2 the romances were VERY buggy, making sometimes it even more attractive to NOT have a romance, when you wasn't able to be sure if you are going to face bug that may even ruin your whole game.