Karlach was gorgeous before they gave her the beauty treatment. Even without hair. She looked much more the part. And as such she was much more attractive than the latest iteration. And the cast had more diversity.
But her voice never matched that awesome look and perhaps they didn't want to redo all her VA.
While I agree with pretty much everything you said, I think it's better to have just a voice that doesn't fit personal backstory than a voice AND face that doesn't fit personal backstory.
In addition, there are voice modulators.
If I can easily make myself sound like Darth Vader, I bet Larian wouldn't have too much of a problem with making her voice sound a little more "rough".
