That's particularly true of tech books. I want to hang on to my copy of "Tinker Tailor" but "Adobe Air in Action" 2008?
Most underlying technology is timeless (see TAOCP, SICP, CLRS, K&R, GoF, Dragon Book, Beej's Guide, Sipser,...); but we seem set on producing an endless, pointless, churn of frameworks and minor language differences in the name of progress.
True enuf, but how often do you actually refer to the books underlying ideas? I've had (now gone, presumably) TAOCP on my bookshelves for years, but how often did I use it? Stuff on RNG a bit, I guess...