In her article, Radical Change, the Quiet Way, Debra Meyerson explains that change is hard; change is messy. If you speak out too loudly you can create resentment towards you. But if you “play by the existing rules” (i.e. remain silent) resentment builds within you. The trick is to rock the boat without being thrown out or falling out of the boat.
Tempered radicals can strike the right balance, making change without causing trouble.
Me, I tend to lack a lot of the "tempered-ness". I tend to be too radical for most people to handle. You don't have to be that way in order to effect change. Change takes time.
For more information see Debra Meyerson's book, Rocking the Boat: How Tempered Radicals Effect Change without Making Trouble.