Surely the newspaper has something better to do than this trivial exercise?
Books are very much a product of the times they are in. These guys had to go far enough back so they could find books that no one would remember, which meant they were dated by today's market. Thirty years is a very long time, especially when you have major events that affected the book market (i.e., Cold War ending, first woman in the military, 911, new technology, audience tastes, etc.).
I recently picked up a book called The R Document, billed as an International Best Seller. I hadn't heard of it or the author before, and I know of most of the best selling thriller authors. As I read the book, I kept thinking that was it was a thriller, but it was remarkably unsophisticated for a thriller despite its subject. Finally, an oddly dated reference made me look at the copyright date: 1976. It had apparently been rereleased because the subject matter was somewhat current. But the book itself didn't stand the test of time and disappeared rather quickly. The writing was great for its time, but it wasn't sophisticated enough for today's market.