What you describe would be pretty cool, but it's also complex and kind of a pain to implement. Larian is willing to go into permutation madness as we've seen with the box, but I think the key with the box was that they didn't really see it coming initially. They made a decision about the importance of the box and got themselves written into a bit of a corner. With this, they can see that level of compexity coming. What you describe would necessitate pretty dramatic divergences that I don't think most studios would be willing to commit to unless it was a specific central part of the game. I don't think it's a societal thing at all, if it were then I doubt Larian would be approaching the romance and sex stuff the way they are, for one thing.
I don't know. Is it REALLY that complex? You show up at the grove. They let you through because, you know, you helped kill the goblins. You meet Zevlor who says (like he does if you're a drow), "Oh. You're a different race (assuming Yuan-ti Pureblood is MC race) I've never seen before. Well, no matter. I'll make sure everyone knows that you helped us kill those goblins." Everyone, for the most part, is then thinking you are an ally.
Then, for flavor, add a character or two who is prejudiced against your race/other races. Aradin, for example, seems like a jerk who would totally be racist. Zorru's scared out of his mind and might freak out if he saw a Half-Orc or Yuan-ti or Dragonborn. In his mind, they might be working with the Gith. Though he's seen Gith, he doesn't REALLY know who they are, so he sees anything similar as a potential ally to the Gith. Maybe a druid somewhere sees you as a "monster" race or recognizes your race and treats you with contempt. Have Volo intrigued. "What do we have here? A Yuan-ti Pureblood! Fascinating."
It wouldn't take an entire reworking of anything. A few lines here and there, and maybe a few "I don't deal with your kind" situations. I don't think that would be too complex.
But then, I also understand that it all adds up. A Half-Orc dialogue here, a Yuan-ti dialogue there, a halfling dialogue there, a gith dialogue there...
