Personally I was never much in favor of the profession books, but for the various crest-related stuff (that are not yet available in the game) they make excellent sense. For the various kinds of crests, and spellshaping gems, sure -- I think we need the profession books, clearly. And this is what Keith originally added the profession books for, and it's not something that comes until later in the game, yadda yadda yadda. That part of the mechanics should work well.
But when it comes to the three main kinds of crafting -- spellgem, spellscroll, and outfitter -- I'm starting to really hate the profession books. It's confusing to new players in all sorts of ways:
1. Where do I get them?
2. Why do I stop finding them after a certain point?
3. I unlocked the recipe, why don't I now see a spell of the sort I just "created" (lack of clarity there compared to crafting).
4. How do I turn them in, especially assuming I didn't read the tooltips?
5. How do I get higher-tier versions of spells if I am not finding more profession books to unlock them?
And so on. Speaking specifically about the main three kinds of crafting only, I think that profession books really need to go. I don't think that they add anything fun to the game, and they increase the complexity for new players substantially and pointlessly. They also increase the literal difficulty even if you understand them, because you need to go to some higher-than-level-1 regions to find them, usually. And as we add lots more spells, the randomization and so forth of what four you can unlock at a given time is going to get increasingly frustrating (and I already find it frustrating).
We could put more time and effort into trying to educate new players on how to use them, find them, and so on -- but I think that's really just mitigating the problem rather than solving it. You already have to find the materials to make spells, and you have to go through the step of crafting them, and I think that's complex enough for the basic three kinds of crafting.
I'm really leaning extremely strongly towards ditching them, but I'm curious about the thoughts of players on it.