If you want it to be in the starting cities, that's going to pose massive issues to any new players if they can't interact with all the NPC's they need to for their first couple of levels, or if they wander into somewhere dangerous without knowing what's going on. I think it would definitely have to be opt-in, and not opting in leaves all NPC's fully interactive for that player. Nothing quite as disheartening as dying repeatedly through no fault of your own (in your first hour of playing your first character in a new game you don't yet know the rules of).

If it is fully opt in, then I fully support it. I'm sure a lot of players would have fun with this sort of idea.

Regardless, I can see you put a lot of work into this so great job ^_^