Humanoid (cheap try to include humanoid races discovered after we made contact) races seem to have a tendency to refrain from killing anything that resembles them closely (pets are not included in this ranking).
The drow don't seem to have any problem killing you if they find out who you are.
Just to get the game stuff out of the way: The beholder dungeon doesn't really need to be cleaned out, you get the prize from the first beholder you meet. Conversely, you don't clean it out you miss an experience farm. You, then, don't need to clean out any dungeon because Andalon will take you right to the door when you've brought your eggs to her. Even Andalon, (LG?) doesn't wipe them out.
Right, so you don't need to clear out either the Beholder nest or the Drow city, even though they'll both attack you given the chance.
Beholder, Kuo-Tao, etc, are more easily demonized because they seem to lack language. Ultimately, I guess, what makes a monster a monster is in lacking the ability to change; lacking reason, wisdom, and ultimately, capacity for compassion. Feel free to expand on or contract this - you bring up an interesting point.
The Drow we meet in Ust Natha don't seem to be particulary compassionate from what I've seen. Granted, there are good Drow, but we also see Beholders that certainly aren't evil...see Spectator Beholder. Or, so I don't have to rely on an awful joke for my argument, the Monstrous Manual also lists non-evil Beholder-kin.
With regards to language, it also says: "All beholders speak their own language, which is also understood by all beholder-kin."
Then, if we want to step outside the BG game world and view traditional monsters in a different light, et's start with the drow: The only thing we see in this drow city is adults. How reasonable is this? They certainly have children? They included a few examples of drow who did not feel as other, perhaps more wicked, drow did - Solaufein and Phaere, even the worshippers of Vhaerun and possibly Jarlaxe. They are all murderous drow with no capacity or capabilty to change, perhaps leave?
And what says this isn't the case with the numerous Kua-Toa, Beholdes, Illithids, and whatever else you happen to slaughter?
But one thing I will say - no matter how many times I play that through I still can't bring myself to corrupt that Kuo-Toan pool. That would effectively kill their race, as well as being an optional act.
This is where it gets sketchy, because this sort of genocide certainly isn't very nice.
Is this your attempt at gauging the reactions?
You mean players' reactions? I love gauging reactions, not so I can mod by democracy, but to see all the alternative viewpoints and reassess for myself.
I didn't realize that the PC gets a virtue increase for freeing Viconia, I assume they get a virtue decrease for letting her burn? ...what was the question again?
I haven't implemented a Virtue penalty for letting her die. Yay, time to expand the discussion. Viconia is being killed because she is a drow, not based on any past actions. Saving her from this fate is virtuous. On the other hand, she IS evil, and as such, it doesn't seem appropriate to dictate that leaving her lowers Virtue.
[EDIT] And just for clarification, Virtue v14 is NOT going to include an Improved Ust Natha component, whatever else happens.