I agree that in most cases peaceful protests don't have much impact when it comes to changing an entrenched power.
There's other ways to act other than burning things, tho. Boycotts were effectively used by India and the black American community to win their demands. Remember that Jim Crow laws were not overturned because of riots... they were overturned because of organized, peaceful actions. The later riots didn't win them jack shit.... it only gutted their neighborhoods.