Fireteam chat would be cool, but no to proximity chat.
If you're trolling, then that was really bad. Players can already chat with other members of their Fireteam.
Not trolling. On ps4 I had to send a party request to talk to anybody. Now that I think about it the way I had chat set up might have been the problem. I just dont want to hear all the trolls yelling at me in the game.