I think the ship has sailed on this, but a rethinking of the design choice would be nice. At least let other characters add INT- and WIS-based skill tests to assist the (usually CHA-based) speaker.

Also, I don't think it is quite as interesting as Larian seems to think for a character who happens to be in front to always be the one who needs to stay in dialogue. A character with better Diplomacy could easily step up and say, "I speak for this group" if the Fighter accidentally triggers dialogue.