I guess my objection to flag-burning is because of personal disdain. I see it as a pointless gesture, designed to anger others rather than proving any kind of point. Just my opinion.
I don't like flag burning, but I recognize the right to express an opinion. I don't like communism, but I recognize the right of communists to have and to speak their beliefs.

A flag is private property, plain and simple. I don't understand people who would break their computers with a sledgehammer, but I recognize their right to own, to use, and to destroy their own property as they see fit.