I agree that the serenity prayer does not mean one should not try to remedy injuctice, on any scale (I cannot say that it urges one to do so though). I intended that to come through by having said: "I have not extended this to mean that we cannot effect change. When I talk about acceptance, I say it helps to practice acceptance on a moment by moment basis without accepting the permanence of an unacceptable situation."
In my essays, I say: "If you desire to change the world, great, I sure do. Acceptance does not mean turning the other cheek regarding either a person or the world. It means, in this respect, do not let the situation eat you up inside."