Decriminalizing everything is tempting.  However, it will only increase addiction.
We had an elderly member of our family addicted to prescribed painkillers. In her case, having access to legal drugs was the worst thing that could have happened to her.
Making them accessible to people who would never otherwise go to illegal sellers can be a societal disaster.

And, no, we certainly cannot trust the pharmaceutical companies to reduce harm.  Evidence the large law suits being won by states and governments against pharmaceutical companies that put these drugs out there.