"Going to the polls" hasn't worked. Allowing the courts to dispense justice has done anything but that. What then? People get frustrated and angry, correctly feel like they have no voice and no options, so they unfortunately resort to violence.
Local businesses being destroyed is a horrible outcome of this, but I can't even make myself feel bad about the police precinct burning. (I do feel very bad for and worry about the safety of firefighters.)
If you want to blame anyone, blame the police for getting us to where we are today.