The main intention of the book was not to be a price guide but a showcase for different cards released at the time. Some of the trophy cards showcased in the books were how a lot of the audiences, specially outside that of Japan came to first know of them. I believe that they kept making these guides till almost the BW era but some can correct me, and it was always meant as a card showcase.
You know it as well as I that making an official price guide on limited release/prize cards is impossible. These books are now part of Pokemon history like Pokemon stamps, coins, postcards etc. They don’t need a practical use.
Cheers!
Edit: realised that 3 year thread was bumped. Apologies.