Civility is strength. It shows that one is in control of his emotions and that he controls himself instead of the world controlling him. It amazes me how so many people engage in rude behavior, falsely believing that behaving poorly gives them power. The reality is that it doesn't. It demonstrates how weak and out of control that person is.
A strong person controls himself. He doesn't give in to the temptation of incivility, even if he is on the receiving end of it. Imagine two people: one is boorish and loud and the other is calm and reasonable. Which one is more effective? More influential? It's clear which person I'd rather be.