It is exactly because of the visceral response it causes that flag burning is such an effective tool of protest. It draws media and public attention, thus giving the protestors the chance to speak to a wider audience than they might ever have been able to had they used other methods. While there might be some rhetorical backlash, it is not enough to make it not worthwhile. In the case of violent response, the ability to exercise a right should never be infringed by the potential for a violent response to its exercise. People's rights should be better protected in that case, not restricted.