One of the unfortunate side effects of criminalizing drug use has been the muddying of the ethical landscape around law breaking. The argument that drug use laws are unjust has bled into a belief that other illegal behavior is somehow excusable when committed by an addict.

So it's not that Portland made a mistake in decriminalizing public drug use. Their mistake was that they stopped enforcing other laws around the misbehavior addicts engage in.