By the way, how would a fully voiced Tav work? You have several dialogue options, like you have now, you pick one and then listen to Tav reading it aloud?
That's how it works in Dragon Age, essentially. Only, there the full line wasn't written, just the general tone of the answer.
And, of course, that game had less dialog options - for the most part, it was positive / joking / negative selection. Still, it added plenty of immersion, imho.