Why? I’m a graduate student in English Lit, and I looked at my reading requirements for this semester and found that the vast majority of the assigned books are out-of-copyright (meaning they were published before 1923), and I can download them free; most are also famous enough to make them easily accessible online. In other words, buying all my books for the semester will cost $200. Buying a Kindle will cost $259, plus another $30 for a case. The Kindle + free books effectively makes the Kindle $59. If I’d realized this last semester, it already would’ve paid for itself. In addition, I won’t have to lug around nearly as many .pdfs as I do now.
Given that the English curriculums appear to focus on pre-1923 texts, I’d be surprised if more English majors and grad students don’t take this path. At the moment, it’s possible to read class books either on a computer screen or print them out, but neither solution works all that well. I suspect this one will, though, as always, we shall see.