If you use Scumbumbo's great Self-Configurable Autonomy Mod (SCAM) there's a neat trick. If you click on the ground and choose control autonomy, then search all interactions, and do a search for "chat", on page two (in my game, anyway) there is something called idle_chatting_stc. If you disable it, they suddenly stop doing all that useless babbling that does nothing but fill time between the rare actual interactions like jokes, brighten day, etc. I really kind of figured this would cause them to just stop talking quickly, but instead they keep choosing new REAL social interactions, one after the other. I have to try it for a while to see if there is some downside to it, but so far it plays like a whole new game (well, the social part, anyway).