I would have listed the suggestions in a different order. Your first one would be my last, and your second best would be my second to last.
The baseline, in my view, should be :
have the party act like a party. Everyone is in the conversation, and so
- If there is an active Ability Check to make during the cutscene, e.g. tied to a dialogue choice (although not all cutscenes are conversations with NPC, see entry to the swamp), I can choose who makes it.
- If there is a passive Ability Check to make during the cutscene, e.g. to notice something or recall knowledge, I can choose who makes it. Or everyone makes it. Depending.
Having a designated party Face would be a disappointing fallback option, I think. The point of a party is to have a range of talents. And I can't predict what skills the coming conversation will need. But I can have my whole party with me.
Aside from this, yeah, I have experienced the issues you described, and it is frustrating to have no control over who talks in some conversations. It is also disappointing that the current version of the game, both in its UI and its writing, assumes that you are basically a Solo adventurer during conversations. Larian said in interviews that they wanted the cinematic conversations to put the focus on the party : it currently puts the spotlight on how the game fails to make the party act like a party.
As for multiplayer, you excluded it from the scope of this thread, so I'll leave it aside.
