From Mark C. Taylor, in an op-ed piece many New York Times readers found worth forwarding to one another.

Graduate education is the Detroit of higher learning. Most graduate programs in American universities produce a product for which there is no market (candidates for teaching positions that do not exist) and develop skills for which there is diminishing demand (research in subfields within subfields and publication in journals read by no one other than a few like-minded colleagues), all at a rapidly rising cost (sometimes well over $100,000 in student loans).

Then consider the Internet. For an autodidact, this is a golden age. For going to graduate school, not so much.