That can be fixed by a joining fire team prompt and a player "volume" area trigger that check if all players are nearby for atleast 5 seconds before dialogue and animations occur from a set stance for the npc model.
[quote]I think they shouldn't try to tell stories in a chaotic multi-player environment, you have conversations being started before everyone gets there etc, people skipping cutscenes for everyone else[/quote] While I agree that this is a problem, there are possible solutions. For example SWTOR (an actual Story MMO) has a mechanic in the base game that Players can only start conversations if every player in the group confirmed or declined taking part in the conversation. While Destiny is not that much Story driven as SWTOR is, I would say it could work if they limit the "activation" of dialogues to "all players must be within a certain area" which also makes sure players can hear the dialogue. But as I said, I agree this can be a problem.