Non-violent protest only works when your opponent has a conscience of some form. This is something government lacks. As long as government continues down the path of ignoring peaceful protest and only listening to mass movements and displays of power violent protest will continue to be necessary and an essential component of any mass movement
Although governments routinely insist that terrorism doesn't work the fact is the IRA won their war. The sad truth is all too often the gun is doing all the real talking and if you don't use one you might as well roll over an grease your butt because these people don't even care if you are dead and will screw you as long as they can.
The same with riots like the one in Charlotte. The Chinese turned it into an art form thousands of years ago and to this day can kowtow with the best of them, only to riot by the millions if they believe nobody is going to stop them from being exploited.