I think that would be to much work as of now to change your character to act differently with every NPC if you are corrupt enough.
What I would like to see, besides our champion corruption other people and more corrupt specific content, is for the game to acknowledge at certain point that your character is not as pure as s/he appears to others.
Like,for example, Kas acknowledging that we are getting more and more amoral by the day. That we do stuff not (only) for betterment of others but for our personal interest. And our champion admiting it.
Now, this would not really fix the feeling of us being the nice guy/gal in some cases, regardless of decisions we make. But at same time, it would, at least to me, make the champion feel more "evil lurking in the shadows". Instead of "that person that does evil stuff once in a while". It also opens the doors to some roleplay aspect. Like "I am just helping Cait to get to her hotter sister, not because I care for her". And it would make our sudden corrupt decisions (one minute we are petting the dogs, next we are kicking them) much less jarring.
Also on that note of making our decisions less jarring. I would like if they would forbid as of accesing some content if we are to pure/corrupt. Like, that would make corrupt system actually feel impactful once in a while. And maybe lock our corruption at certain point. That way, it makes our decisions have more weight to them and it gives more replay value to the game.