Personally, I don't mind reading and I wish we'd get more games that don't require voice acting for everything. It'd allow them to do so much more with a lot less. I do think at some point we'll get that that point with synthesized voices, but it isn't quite there yet. I've used several in Ludum Dare games, and they sound great but not perfect. Still, even as they are if they let devs write more and create more options, I'd take it. Adding options with voice acting balloons work required fast, so that's why it's so often fake choice but the other person (or, in FO4, the player character even) responds similarly no matter what you say.

Would need to lean on AI for something like that, I think. Keep the normal human-acted main cast/supporting characters, delegate everything else to AI.

It's already been done with a Skyrim mod.