I will add to that, that that is something I want from a singleplayer experience as well - as there is no "party leader" it is annoying when NPC initiated conversation with someone I didn't want them to. It's also awkward to go through the same conversation with multiple characters just to do the right skill check. Talking as a party, rather then an individual (as long as we are in the vacinity) would I think make for a much better single and coop experience.
As far as I know, after Patch 4, NPCs always initiate a dialogue only with MC.
