Burning a flag is a very strong reaction, and if you're not allowed to show that you seriously feel there's something really wrong then that's an infringement. You should only be allowed to do it if you have a very strong opinion you disagree of with your country. I'm not patriotic, but I'd be irritated if someone did it in the good situation Sweden is in now. But if someone's been betrayed by our society, why not?
Tell you what, if you make it illegal to burn a flag, it'd be an even greater tension in doing so, and then you'll definitely see it happen more often.