What do you think could rectify this issue of a weak willed population?
I think is a situation of "natural cycle of empires." A burgeoning empire will have a collective will of the people for communal growth. Once it reaches a certain level of influence and power and easy of living for its members the will for progress dies because the essential challenge is lost. What remains is only a will to enjoy the happiness attained. Where there is no larger, grandeur, objective for a nation of people aside form just maintaining the norm then acceptance and even retrograde seems to begin.
Our educational system is the top of the planet because it was established alongside an empire building itself. It grew alongside an industry free and open demanding talent. It grew alongside a country with an elite class just waiting to be populated. And lately in the past century it was World War 2 and The Cold War which kept education (and industry) at the helm of government objectives.
Today, we really have no grandeur objectives only that to maintain the top spot. The people are becoming less interested in education because they rightfully see less and less of the need. Its no surprise that graduate programs throughout the nation are populated by non-western foreigners and why the government has to give mandates to hire Americans, as Rumbo pointed out.
We can't simply TELL American students "hey, be interested in science its going to help us." The people have to FEEL the need, understand the need.
I really think its a natural cycle of empires and there is really no avoiding it. Only after America has significantly lost her power and influence then its spark will be reignited*
(* or a nation-threatening War. A War supported by the people always helps too...)
EDIT
What can also help is to open up our borders more to foreigners. Let Americans see what lack of interest in education is costing them. Yes, talent might be taken back oversees to home country but so will Western Ideals, American favor-ism, and capitalistic notions all of which will indirectly help us to handle and understand a global economy.
Protectionism and Isolationism is the VERY LAST thing this country needs.