Welcome to the cult club!
It's a job that really rewards practice and mastery. The difference between a good Black Mage and a poor one is night and day.
It doesn't, as far as I can tell, benefit the Dancer directly. It functioned identical to a weaponskill anyway.
It does however benefit others. It means it can contribute to things like a Monks Brotherhood, Reapers Arcane Circle or another Dancers Espirit etc.