Except the highly visible destruction and violence by its residents leave a lasting impression of what the community is actually composed and capable of at any given moment. The riots just put it on display front and center.

You can just stay indoors when the weather forecast is bad. There's no way to keep all the riff-raff locked inside while your kid walks home from school. In a place like LA, there's a lot of riff-raff. Just because there's no active riot doesn't mean the riff-raff is gone, they're just not all in a frenzy showing their true colors simultaneously. They continue to exist, and continue to be a potential risk, at all times.