I agree with your post OP, but after reading it, made me think of another idea.... I think it'd be really neat to have books crafted by MULTIPLE DOH jobs. There are all kinds of different books, they all range in size, color, variety of materials for pages, and as you imply in your post, the cover is the most time consuming part of making a book.

I see where you are coming from OP in considering leatherworker, and that would work very well for a leatherbound book, or a cover that used tannery, but I can very well see a book with a wooden or bark cover, made by carpenter...or possibly a book that is decorated in jewels that could be engraved with gold or gold plating, crafted by goldsmith. I could even see the possiblity or feasibilty of a book with a cobalt cover or a book crafted soley from fiber....

I think books that can be crafted, their recipes should be distributed amongst all DOH jobs so there can be more vivid and vibrant possibilities for Arcanist. I think it only makes sense this way.