Socialising substituting for thinking
Groupthink is pretty stupid when left to its own devices, but is fairly simple (but not necessarily easy) to fix: Provide leadership. I don't think that the trashing was all that organised. Trained and well-led trashing operatives could've done far more damage. The most iconically burnt-out building was a carpet shop. Once that gets going, it doesn't stop, regardless of how it started.
I think the damage done says more about just how fragile our shopfronts really are. They're not mob-proof. This stands to reason because shops need to make money and so they need to attract customers, and can't afford to look like a prison or a bunker.
The official response was both blindsided (everyone was) and frankly overwhelmed. That too is a sign that things are usually pretty cosy; there normally isn't that much need for plod. The aftermath, though, is equally inevitable and shows us the weaknesses in the political system: Knee-jerking all-around. The fall-out of that is probably worse and definitely longer lasting.
So after the riots subside you need to take out a big large cluebat and make sure the political mob doesn't go too berserk in outraged posing and indignified grandstanding. Almost everything proposed will be shallowly aimed at symptoms, as nobody is willing to dig into the icky murky depths of the problems of society and do something constructive about them. It's the aftermath that's really telling on our leaders, and I have seen little to distinguish them.