David W. Lewis has self-archived "Why Book Selection by Librarians No Longer Matters."
Here's an excerpt:
Prediction about the future use of a book and using this prediction as the basis for a purchase decision only matters if the time required to acquire the book is greater than the time the user who needs the book is willing to wait for it. . . .. With print-on -demand and overnight shipping most print books can be delivered in 24 to 48 hours, which meets the needs of many users. This means that prediction of possible future use whether by expert librarian selectors or by algorithms, such as approval plans, is unnecessary. No prediction is necessary if the needed books can be delivered quickly enough to satisfy the person needing the book.