What I took away from it was that weed use/problems among kids have been on the decline, and decriminalization has apparently done nothing to reverse this trend. Which has been one of the stated fears: If you legalize it, then everybody will start doing it that wasn't already. That's evidently not the case.
Yes, I think that decriminalising marijuana probably does decrease its allure. All people, but especially teenagers, are drawn to things which seem exciting and unobtainable. I suspect that it is also more openly discussed so the risks of smoking cannabis at a young age will be widely known which will aid in decreasing its use. I would also presume that as it is now a legal drug that it is more expensive to buy than when it was illegal due to taxation and the costs of advertising and marketing.
Decriminalizing marijuana would remove some of the allure for young people to try the drug. When some are told not to do something, it can actually make them want to do it even more. This was proven to be the case during prohibition when many that did not drink before, began to drink after sales of alcohol were banned. This is likely the case with marijuana and teenagers: many try the drug because it is against the law.
With Colorado reporting the lowest rate of teen marijuana use in the country, decriminalizing pot does seem to remove its allure. However there are two groups, one opposing the view and the other supporting it. Nevertheless, as far as research surveys show, there has definitely been a drop in marijuana use among teens in Colorado.