The article you cite tells exactly why Uruguay's experiment has failed; they haven't actually legalized. "As of early 2016, however, pharmacy sales remain unavailable, leaving only the 6,000 Uruguayans who cultivate their own plants with legal access to the substance."

The country has a population of 3.5 million people and marijuana has been legalized for 6,000 of them. That is not a sensible route for any country.