An artist in performance should be relaxed, natural and never exude an air of importance. They should also not be over-dramatic as this unsettles the audience.
They should win over the audience in their gentleness and good nature. 'I am playing for you as a friend, not as a stranger, nor someone superior to you. I am sharing this music with you and hope we are celebrating it together'---these should be their words.
It's easy for performers to estrange themselves from their audience, and, in spite of their brilliance, by not possessing the above attributes.