In an NYT article about drastic changes in application rates to various colleges, Ivy League type colleges as well as elite state schools are seeing lots more applications this year, while elite liberal arts colleges are seeing no change or a plummet in their applications.
The common factor to Harvard, Stanford, UNC Chapel Hill, and UVA, and which is absent at Williams, Middlebury, etc., is that the former are big research institutions where the faculty get a lot of shit done, while profs at liberal arts colleges -- and even the physical campus itself -- tend to be very isolated from the real world.
Going to Williams rather than Columbia is like bragging that you majored in French lit rather than physics or economics. It's a signal of conspicuous frivolity. Therefore, it's no surprise that, just as their parents are slashing their handbag and vacation budgets, teenagers are going with a more surefire way to financial stability.
It rubs off on smart, hard-working young people when they're surrounded by role models who don't accomplish much, while being surrounded by workaholic researchers better enculturates them into the real world.