Americans are disappearing from graduate schools for two simple reasons:
1. In many fields, it's a waste of money and doesn't make you any more employable than you were with a bachelor's degree.
2. In fields like mine, there's no huge incentive to attend graduate school because you can make a good salary even with an undergraduate degree. In fact, I don't value someone who pursues a full-time master's degree in my field. They're 2-3 years behind their peers in terms of work experience, and they always seem to be the most impractical employees when it comes to working in the real world.
In the oil and gas industry an engineer with an MBA is management material.