These drugs chemically change the brain, so your brain might fall into a state where you lose control.
Drugs often get pulled decades after being approved, usually because the safety studies were not expansive enough to give a complete picture of the danger. For example: Varenicline.
Just like all drugs, but the downsides of criminalization have been obvious for decades. I don't see a solution that isn't all drugs being cheap and legal.
Cool world that would be to live in.