Well, it's hardly surprising. The young person who is in love with English literature might genuinely want to pursue a major that takes Shakespeare, Jane Austin, Dickens, and the notable poets from the Beowulf author through John Donne and Milton and down to Seamus Haney seriously, but will not major in English when he or she discovers that all the courses are taught from a deconstructionist or Marxist-feminist or post-Colonialist perspective and denigrate the very literature he or she fell in love with as either meaningless or the "product of dead white men" (okay, Jane Austin aside, but she champions outdated and oppressive, blah, blah, blah...)
The same goes for would be philosophers who attend schools where the philosophy department is overrun with "feminist philosophers" and the Continental types who follow Derida, modern language majors whose departments are enthrall to similar forces to those in English departments (so that all the courses after those that teach the language qua the language are spoiled), history majors who might want to study major historical events but find most of the required coursework is on "social history" taught from some exotic cultural leftist perspective.
The humanities are, aside from university administrations, the place where the rot in American academe is the worst, and students see this and pick other majors.