I absolutely agree with you. However, writing such a book needs time, experience and writing skills; we simply don't have many people left who would have all of this. Plus, the Amiga market is quite small, so the publisher of such a book would have to be a huge fan doing this for the cause, not for profit.
I can attest to that. Sales of the Warp3D Nova tutorials book would have to be whole orders of magnitude more than it is now if I wanted to make a living off it (as in earn enough to keep a roof over my head, food on the table, and keep the lights on).