I was discussing this just the other day... or trying to. Folk music deals very directly with the human condition: birth, death, tax fraud, etc., so it has a cathartic effect. I remember June Tabor calling this, 'The purging of emotions through pity and terror'.

In other words, it's like lancing a boil. Folk songs are a bit like free psychotherapy. I'm good to go after a sesh with Child Owlet.