How do you account for different races? Do you think half-orcs and halflings sound the same? Dwarves and elves? Humans and gnomes?
Good point ...
Step 1. create proper voices for allready existing system ...
Step 2. find a way to expand it.
So far Larian didnt make even half of Step 1. (there is no proper Dwarf voice for PC) lets not be greedy. :-/