As a french guy, I know that strikes and rioting are necessary for things to change for the better. I just need to look at the History of my own country to understand that.What I disagree with is your stance on looting.
I don't see the material damages as the biggest issue here. In fact my real issue is that I've always felt like the people involved in those activities had nothing to do with the people rioting in the first place. The " cause " doesn't mean much to them. I feel like the people protesting to improve our society have too much respect for the cause they're defending to resort to looting. Where I agree with you is that when there's rioting, there's a big chance that there will be looting. But I won't go as far as saying that looting as a part of rioting. Looting is one of many possible consequences. And it's an avoidable one. So I think you're wrong when you say that " looting " is only natural.
Now the problem is that in the public perception, there isn't much difference between protesters/rioters and looters. And this is an issue everywhere. In your first post you talked about the May 68 events in France. Well as your quote pointed out, in the next election french people voted " en masse " for De Gaulle to restore peace and security etc... The vast majority of the French people didn't give a fuck about the legitimate causes those students were defending and all they wanted was to preserve the status quo. Between the protesters and the police officer, your average citizen will always choose the latter. That's why looting isn't " necessary " at all but also looting doesn't really " kill " the message as much as you would think. But I also have to say is that De Gaulle was a great president (the best we ever had) and a war hero but this is off-topic.
In the end, I think that in our day and age, same as 40,50,100 years ago, the best way to make change happen is to go on strike and " paralyze " the whole mecanic. I don't think there's much hope in rioting nowadays. It might work if it's a concerted effort throughout the country. But still it might turn against you. People are way too attached to their little confortable lives to give a fuck. I feel like if you want your voice heard, you need to really interrupt the smooth running of the institutions. Starting for instance with the public transport. When people won't be able to go to work in the morning that's when they'll start listening and they'll turn to their government and urge them to find a solution.