What those guys think the flag is doesn't change the fact that it is just a piece of cloth.

I don't deny that those guys associated meaning with the flag. But do you deny that some people hold a less favorable interpretation of the meaning of the flag? And certainly not all citizens believe the common interpretation of its meaning is a good thing. Do you think that we should not give those people the freedom to express their political opinions or that expressing those opinions does not include allowing them to burn the flag?

Why should an individual not be allowed to use his own property as he sees fit, to protest as he deems necessary? Is it simply because some people hold a deep respect for the flag? Heck, we could make it illegal to disrespect the cross if that's the case. But I think we shouldn't be preventing people from using their own property to express their own beliefs simply because the majority holds different beliefs.