This has actually been a thing since Rodney King, you likely just haven't noticed.

Hell, when the cops who killed Malice Green went on trial, the glipglops were all gathered on street corners, just waiting to riot if they didn't like the outcome. But they were found guilty (as everyone knew they'd be), and they all went home without bothering to do anything. I'm damn sure this sort of thing has played out in different cities since.

This is just higher profile stuff, crap shoved in your face for political reasons.