I agree with this. I want to play through the game with a friend and it seems like one of us ends up missing half of the dialog. Even if you try and use the chat in the corner all the random one liners from "citizens" and such just bog down the chat window and make it hard to get a clean flow of the main guy you actually want to hear.
I like the ambient background chatter, but I want to be able to see what the main dialog is that is going on INCLUDING the responses from my friend and not just the NPC side of things.
Not sure how no one ever brough this up or found it frustrating in all the tests that have been going on. Seems like a pretty basic piece to the game.
