Illustration album in the tempest shop

What does it do? and what is the exact point of putting all those pictures in the tempest shop for coins? Seems like a waste of coins unless you like collecting pictures. The album's description states it opens an 8 slot bag, but I figured it was just for the stupid illustrations.

thanks in advance

I bought the book with 8 pictures. It's just pictures that you can look at.

Do not buy it.