My suspicion is that philosophy is a dead field. Psychology and neuroscience are coming out with fascinating new results backed up by facts and studies.

For instance Jonathan Haidt comes from social psychology, and his work on moral foundations is far more interesting than anything that's come out of philosophy departments this century. Even though morality is supposed to be on of their core issues.

Once they get tenure they're forced to face the fact that they have no more career goals and can't do any meaningful work.