The Afghani people make good use of the few resources they have. Who could blame them? They used opium and heroin aggressively (and effectively) to suppress the fighting capacity of the Soviets.
The Taliban's "suppression" of opium cultivation was purely for show. People there have been growing it for thousands of years, like the coca farmers in South America. It doesn't matter who is in power. They're not going to stop growing opium in Afghanistan, ever.