I agree that giving amphetamines to children is absurd, but they are a very powerful class of drugs; and therefore, like opiates, they have their uses despite the obvious negative effects. Drugs are dangerous. So are automobiles, heavy machinery, chemical plants, etc. If you know how to use any of these things properly the payoff is worth the risk.
Also take into account that less than 50 years ago, you could buy amphetamine inhalers from any pharmacy in the US (and plenty of other places) without a prescription. Change takes time. On the other hand, 50 years ago, plenty of products contained chemicals which are now known to be toxic and carcinogenic, and amphetamine in comparison is pretty benign.