When we are together we can absorb every nuance of the other person’s stance, facial expression, reactions. Often, these indicators will help us in our communication because we might alter what we are saying next, based on the reaction to what we have said last. This communication feedback may be why we are diplomatic and sensitive. The lack of human feedback may also be why we are insensitive via text and email.
Feedback also helps us to clarify the message. A fairly innocuous message can become ridiculously overblown in the absence of human feedback. The receiver does not know what was meant and if the receiver is someone who suspects that the world is bad, the receiver’s bad thoughts could dominate fairly quickly. It’s called a misunderstanding.
Think about it this way, when communicating we are always in a state of emotion. In the absence of feedback and in the absence of clarity, we may end up responding quickly and most assuredly inappropriately. This is why I think email bullying is so common. I think that in the absence of a face and human gestures, we may forget that we are, indeed, speaking with a human being.