Why the emphasis on 'unarmed' arrestees? Americans have the right to bear arms. 'Armed' includes knives as well as guns. Оf course people living in dangerous areas are more likely to carry a weapon for self-defense. I would want to know if the person *brandished* a weapon or otherwise threatened or resisted. Unfortunately, we often have only the officers' word.
Regardless, your overall point is correct, that attention is misdirected. There are several root causes, and one is tractable: Drug Prohibition.