Change usually happens very slowly, even once all the serious people have decided there's a problem. That's because, in a country as big as the United States, public opinion moves in slow currents. Since change by definition requires going up against powerful established interests, it can take decades for those currents to erode the foundations of our special-interest fortresses.
Take, for instance, "the problem of our schools". Don't worry about whether there actually was a problem, or whether making every student devote her school years to filling out standardized tests would solve it. Just think about the timeline. In 1983, after some years of pundit throat clearing, the Carnegie Commission published "A Nation at Risk", insisting that a "rising tide of mediocrity" threatened our schools.
The nation's biggest foundations and richest people slowly roused themselves to action, and for three decades we haltingly applied a series of fixes and reforms. We've had Race to the Top, and Teach for America, and charters, and vouchers, and … we're still in the midst of "fixing" education, many generations of students later.
Even facing undeniably real problems – say, discrimination against gay people – one can make the case that gradual change has actually been the best option. Had some mythical liberal supreme court declared, in 1990, that gay marriage was now the law of the land, the backlash might have been swift and severe. There's certainly an argument to be made that moving state by state (starting in nimbler, smaller states like Vermont) ultimately made the happy outcome more solid as the culture changed and new generations came of age.