The Greeks are useful here, having made sure to embody injustice in emotion, and even song, not just instruction. Their theater depicted the way policy and character were inseparably bonded. As such, “Suffs” is already good, in both senses — a good show and good for the world. I even shed a few political tears. But to be great, a musical (like a great movement) must grab you by the throat. “Suffs” too often settles for holding up signs.