Pros
1. It helps keep the tower's description. To meet up with other guardians and form fireteams. Without proxy chat its a bunch if back and forth of time consuming messaging.
2. Simple, it is easier communication
3. It would not be a way to hear everyone in the world. Proximity chat would enable you to only hear the people near you
Cons
1. Crowded areas would provide a large jumble of multiple speakers
2. The possibility of no mute button
This was semi on the spot. Comment any other pros or cons you have!