See, there's a difference between thinking it an acceptable form of protest and being willing to do it. I have never considered burning a flag other than a retirement ceremony. I have no problem with others doing it.
I have to admit though, I would be willing the burn the current flag if I saw something I wanted to protest, NOT because I can't express myself in other ways, but because it garners a forum in which you can express yourself to a wider audience.
I would never even consider burning the original US flag though. I respect that government.