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.
Well you character needs to be from somewhere ...
And if talking goes either to question where you are from, or someone is talking about THE place you are from ... your character needs an option to respon to that.
Tags obviously help developers to recognize wich character should be able to respond to what ... (im not sure they are visible in patch 7 tho)
So the tag "is there" so your character "can be" a Baldurian obviously.
Of course why give us options not to use it either, it's just a backwards way of doing it.
And you have option not to use it ... so your character "can be" anything else.
And its not working only for Baldurian ...
You are totally able to get through whole EA as a surface dweller Drow ... by simply not picking even a single dialogue option marked as [Underdark].
Not quite sure how to explain non-planar Githyanki tho.
