Up until the Soviet era, a lot of the natural resources Afghanistan has simply were not relevant, or maybe that fits it better, there were easier ways to acquire them than a country thousands of road (!) miles away from the powers that were.

The Soviets wanted Afghanistan for imperialist reasons, during the first Taliban era there were enough other sources that were more convenient, the Americans lacked the conviction and coherence to follow through... and now the Chinese are swooping in with money.