You have no idea of what you are talking about. Legalized drugs in China resulted in the deaths of around 100 million Chinese. You simply have no view of the larger historical picture.
Drugs wrecked China and killed Millions. It was horrible, it was ugly and it was brutal. Far worse than anything being discussed in reference to the "War on Drugs."
Drugging a Nation:The Story of China and the Opium Curse
What you are suggesting would be the "stupidest mistake in the history of the country."
Actually you’re the one who doesn’t know what you’re talking about. Opium was PUSHED onto China, they were trying to get it out. Meanwhile it, and all the other drugs, were legal in most of the world without having issues.
The stupid mistake is adding a black market to the other problems of drug use. You have all the same number of addicts, higher prices, more crimes, and an ever increasing police force. At least with it legal all we get is the junkies. And the only way it gets anything like China is if a government (possibly even our own) decides it’s in their best interest to give us LOTS of drugs for really cheap. Which would be a problem even if it was illegal (as seen in your own link because during most of that time China was actually trying to PREVENT opium being imported into their country).