I think the point is that if everyone (Not Underdark or Gith) is given a [Baldurian] tag then why have the tag at all, unless there will be other tags in the future. Of course why give us options not to use it either, it's just a backwards way of doing it. As though it'll never be important enough to dramatically affect dialogue or the story.
If you are given a [Baldurian] tagged responses and some generic responses, either you (the player) are deciding with your choice if you're from BG or not, or if every option is valid (i.e. you're Baldurian) you're choosing an option that is generic for the sake of being generic.
Some games let you flesh out your character with some expositionary dialogue but I it doesn't seem like BG:3 will be like that.
