My thesis is that the academic novel stems from the rise of mass higher education in the United States. It follows the demographics; the fact that two thirds of Americans go to college provides an audience. College is no longer a cloister but as common as the shopping mall. (For good or ill, it seems England is trying to catch up to this American tendency.) Professors were rare in the U.S. in 1900 — only about 1 in 3,167 people was faculty. Medical doctors and lawyers were much more common — about 1 in 600. However, by 2000 professors came to constitute 1 of 243, so they were a familiar professional to most American people — especially to those who read literature, who in all likelihood went to college.
Also, the novels show academe not as removed but in the thick of public culture, embroiled in the culture wars and subject to the vicissitudes of adult, middle class life. The academic novel no longer depicts a pleasant enclave, but faculty are subject to pressures that any other professional experiences. In fact, one wing of the recent wave depicts those just hanging onto tenuous jobs in academe. It’s no longer close to a sinecure. In short, the academic novel portrays class in the USA, touching a chord with the reading public.