I've come to wonder lately. Do we ever hear of Jedi being referred to as light side in the movies? I just find it awkward that they're the ones supposedly going for a balance, yet popular (and even EU) opinion has them iconicly light simply to be a polar opposite of the dark side sith. It definitely seems consistent with their attitudes. Jedi are reserved and mindful, not controlled by emotion, where as the dark side is fear, anger, and hate. Diametrically the light side would be one of love and joy.
The Jedi ARE the grey side!