It really shouldn't require so much tedious tactical work for the main character to be the main character. So please... make the automatic dialogue system prioritize the main character.
Agree! I hope they make this change. It is very frustrating for a companion to get dialogue that starts automatically instead of the main character.
So what would happen if your "main" character far away from the conversation? Would it talk telepathically? Would it teleport? Would it walk to the conversation? And since companions may have different dialogue paths as your "main" character, what if I want this companion to talk in that situation?
For me, it sounds like a global toggle with an option to right click to choose who will walk to initiate the conversation is the optimal choice there (man that's a lot of "to" in that sentence).