Maybe because it is genuine: people in the picture don't seem to have any hidden agendas - one woman is talking, one is listening, each with ease and interest, sort of like their attire - not haute couture but thoughtful, even happy.
This is one of those rare occasions when I am struck by things not appreciated by the masses. Usually, I'm with the masses. I'm not even sure why this image continues to impress me, but it does. Highly underrated. Congrats on getting it on your profile row though!