Interesting. Decriminalization is one thing, if they are speaking about not arresting people who are just buying it to use personally. I once read that someone was charged with possessing as little as something like 0.04 grams of cocaine. Basically, 40 milligrams. A quantity that you could probably dust off a $20 bill in Florida in 1980.
It may not have been exactly that quantity, but I remember it being ridiculously low.
If this just prevents drug users from facing drug charges, I don't see an issue. Legalization of marijuana in Canada has been a bit of a mess, but in time, may sort itself out. Decriminalization was in Ontario around 2003 for a period of time, and that seemed to be fine. So far, decriminalization has not been that smooth - but most likely, that is due to ridiculous marijuana regulations.
I'm ok with social justice politicians doing something like this, in the sense that I think it's a valid point to say that people innocent of any actual crime against violence or property are being harmed by these drug laws.
But next, I don't doubt that SJW's in Oregon will demand that purse-snatching become legal.