The college-for-all crusade has outlived its usefulness. Time to ditch it. Like the crusade to make all Americans homeowners, it's now doing more harm than good. It looms as the largest mistake in educational policy since World War II, even though higher education's expansion also ranks as one of America's great postwar triumphs. Consider. In 1940, fewer than 5 percent of Americans had a college degree. Going to college was "a privilege reserved for the brightest or the most affluent" high-school graduates, wrote Diane Ravitch in her history of U.S. education, "The Troubled Crusade." No more. At last count, roughly...