You absolutely cannot always see peoples lips or know they are talking, so the ventriloquist argument is moot. People wear helmets, hoods, ect. There also might be multiple people in a circle, with some listening, and some talking - you would know who is talking on an OOC level if you could actually see them typing. We are quite literally discussing a meta-component to add to the game here. The context clue of people having a quiet conversation is them being in close proximity, and you not hearing it.
I hard disagree that the toggle is the cheese. It is the other away around, and it should be optional.
Edit; Just to clarify, I absolutely agree that this is quality of life. Turn it on by default for everyone if you want, my argument is simply let us turn it off like other modes since it is meta information.