False dilemma -- we can address the root causes and also add measures to prevent violence when those causes are not addressed effectively. The OP's point is sound and if you start the argument against universal surveillance by claiming it will not reduce crimes such as these you will not be taken seriously. The question is not if crime will be reduced but at what cost is it worth it. The cameras are coming and the bottom line is we need to decide who sits behind them: a select few, or everyone.