Great ideas in this thread! There are some things that turned on the red light in my mind though 
If the reason for the books is so the crafters can level up and learn new stufff… Where do the writter get this knowledge from? Furthermore, the system already makes hearthlings level up and learn new stuff by “experimenting with crafting”, so would this not just be more code to aclompish the same result?
The number of workbenches… why could the writter not use the same workbench to create paper and ink at? (teasing: oh we could have another class to make paper and one for making inks?) I hope my way of pointing out the weigth in the subject is received positive as i intended 
BUT, i do like the idea of a writter, and certainly books, my favorite class token are the clerics!
The idea with the xp boost from a book that took a long time to make and that could be sold instead for a good amount of gold, seems very usefull to me.
On the matter of ink… Could the herbalist not make it? It would just be adding a new recipe to that class? The paper could maybe be made by the carpenter or even the herbalist aswell? Then the writter could just use any writting table in the city when scripling down those books 
If the developers dont pick this up im sure a modder will… there even was something along these lines a while back if i remember correctly… well not quite the same, but there are some books haha 