Yes, this aspect definitely needs improving. There have been previous discussions on this topic, but it’s worth boosting as it’s not addressed in the latest patch.
As has been talked about before it’s not totally straightforward to have party conversations if Larian want to preserve the ability have one party member in dialogue while others sneak about and do other stuff while the NPC is distracted, which I do think is a nice feature. I’ve thought in the past that it might be good if all party members chained to the one that initiates conversation are considered to be part of the discussion, or others have suggested just everyone within a certain distance who is visible.
With respect to active and passive checks, I agree that all party members participating in the conversation should get a chance to roll if the option is one available to their class/race and chip in if they succeed and the conversation leader fails. I’m not sure how well the exclamation mark suggested by the OP would work, and in fact I don’t think you can currently see teammate portraits in dialogue, but the party member or narrator could to have an appropriate line of dialogue to interrupt and handle the handover.
But then there’s the question of how the handover works. Is it just that the game manages a temporary involvement of another party member when they pass checks the leader fails, or can we actually change who the conversation leader is during the course of the conversation? And if the latter, how? Do we use the existing function to swap party members in conversation which is a bit clunky, or is something better needed? And if we can swap dynamically, I think we’ll need new dialogue lines for characters responding to lines of dialogue that an NPC that would not have said to anyone of their class/race.
Plus there’s all the complexities because dialogue also needs to work in multiplayer.
The game’s dialogue system must already be hugely complicated and adding the ability to have other party members contribute will surely make it worse, so I’m okay to accept that whatever system Larian end up with will need to make some compromises to avoid truly unmanageable numbers of lines of dialogue. But I think it’s hugely important that at least some effort is made to include the wider party more in conversation.