Feedback can be a strong motivational factor, a source of information and a basis for improvement in a variety of contexts. On top of all that, feedback is an essential tool to support good collaboration.
At the same time, feedback disturb and slow down progress. Usually we do know some rules to give and receive effective feedback. We know the intent and we know what to do and still we are often "unpleasantly touched". To give and receive feedback in a comfortable way is an art that can be learned.