Yes Virginia, riots can solve problems:
Many governments and political systems have fallen after riots, including:
Tsarist Russia
The Confederate States of America, for example after the Southern Bread Riots
Ancien Régime
British rule in India, when bread and salt riots hastened the withdrawal in 1947
Governments across the Middle East and North Africa during the Arab Spring
http://en.wikipedia.org/wiki/Riot
Not to mention all the labor movement related riots. Without rioting, you folks would still be working twelve hour days.