Anytime people protest they unify in order to be heard by their government body. If no one ever says anything that gives a license for corruption to be revealed without consequence and people will have to live with that everyday. Protest allows for national and even sometimes global attention so things can change.
I think that it is better to prevent protests in public, because they can end up in a lot of violence for the public around these protests, and it is not fair to put innocent peoples lives in danger. They need to make sure protests are kept under close control.
In the few years in between campaigns, the people need a way to let their representatives know how they feel about issues as they rise up. Sometimes a representative will be unaware of the people's support because he or she is insulated from public opinion. Public space protests allow these voices to gain momentum.
I am all for public protests when things start to go south. It shows that the citizens actually care enough and will go out and be engaging. And I want protests to be a little more vigorous, without turning violent. Holding a sign and chanting a corny catch phrase does not work.
Peaceful protests should be allowed in public spaces. People should be able to voice opinions and inform and debate with others about matters as a means of information for those that may not know about an issue. It also allows people to see different points of view and make informed decisions.