I knew two gals in NM who were fond of the stuff.
Andrea would pop a couple of "Truck Driver" or "Skinny" pills, as she called them, a few minutes before putting Satan's Spawn (her daughter) on the bus on a given morning. She would then proceed to speed clean her house, popping a couple more with a cocktail lunch, then finish her thorough job - as if the Queen were arriving, before the Hellian and Husband of the Year arrived home...
Saundra liked to pop handfuls (5 or so) with our companions boarding the "Party Honda" or whatever to Juarez... (just imagine going 100+ miles/hr with hopped up "adults" en route to Mexico, loud music, beer flying everywhere
). It was their pre-party, co-party happy helper to partying until 4:00 with mas cerveza, hitting Denny's then driving ~85 miles back to base.
And those are the reasons I have found that people have used it - to keep you moving and to keep you partying. And I'm not saying that it's altogether bad. I'm not, really. I've used it. Not in high amounts like those above. I don't think it should be banned, just not available to minors. Give them time to grow up before they screw themselves up like everyone else.