Actually, most fields do not change at a rapid-fire pace, and even if they do, there are important books in fields ranging from anthropology to mathematics that are decades or even centuries old and yet have not been surpassed. One example I came across recently is Gérard Genette’s Narrative Discourse, a classic of Narratology, published in French and then translated in the early 1980s. To say that this book should be removed because the field of Narratology has continued to advance is ridiculous!
Perhaps your idea of what a library’s collection should be is more in tune with a public library, where most collection development policies put more emphasis on currency and popularity. The very purpose of an academic library, in addition to being a glorified coffee shop and study space, is as a resource for scholars and students who need something beyond what they can find at a public library. I know that this is the case for me.