The idea of protest is very important. Whether or not it actually does it's intention is hard to assess. Riots are quelled quickly and usually results in military response. It is to be determined how much leaders are incentivized to listen to their people based on the event of a riot.
Rioting needs to happen within a certain set of rules, but the nature of a riot is one in which even established norms are likely to be broken along the way. Best case scenario is that nobody is hurt or put into direct danger, and the assets or property of people are not being ruined.
If you have a corrupt government, especially one who is run by a dictator who treats his people like garbage, rioting is a viable means of protest. Absolutely it is. What else should they do? Gather outside of government buildings and demostrate peacefully to a government who will murder them?
Rioting is often one of the last forms of protest after many other peaceful ways have failed to bring about the change that they are seeking, I think when people turn to rioting it shows the Government that the citizens are serious about this issue and it will quickly turn violent if things don't start to change.
No, public riots are not quite a viable means of protest. While riots are attention grabbing, they often cause more problems than they solve. Once riots are taking place, the focus typically shifts toward resolving the issues that have arisen due to the riot, such as injuries, deaths, robberies, or vandalism.
No, rioting is not a viable means of protest, because there are people who are victims of the destruction caused by rioting. Rioting is no different than other forms of terrorism, where people seek to impose their way of life or their laws through threats and intimidation of others, often innocent people.