That is exactly what these protests are - part of the democratic process. To show the majority, who are not affected by police criminality through a combination of race and chance, the severity of the grievances by the minority who are.
As for the decentralization argument - I really don't want to be on this side of the states' rights debate, but that ship sailed a long time ago with regards to civil rights. It's not terribly unreasonable that individual rights are protected by state governments ior the federal government when an individual state is unwilling. Although we are currently witnessing a direct failure mode of this centralization, with the federal government having gone AWOL with regards to enforcing the law and even inciting lawlessness.
As for the decentralization argument - I really don't want to be on this side of the states' rights debate, but that ship sailed a long time ago with regards to civil rights. It's not terribly unreasonable that individual rights are protected by state governments ior the federal government when an individual state is unwilling. Although we are currently witnessing a direct failure mode of this centralization, with the federal government having gone AWOL with regards to enforcing the law and even inciting lawlessness.