If anything, this whole episode now labeled the entire anti-globalization movement as a bunch of hooligans who want to destroy things. Even if they did have a cause or message it is now lost as the credibility of the entire movement has been discounted by the general public. I doubt their will be any sympathy for their destruction and most likely many people just wasted their time going to the demonstrations.
In my mind this is similar to any conflicts around the world when few extremists decide that they take matters into their own hands and instead of moving their cause forward, they completely destroy the legitimate questions that the rest of the world was asking about the situation.
Sometimes I wonder if these few extremists were actually working for the other side just to discredit that movement itself!