Enchantment "deny list" for Enchanting Table using Chiseled Bookshelves with Enchanted Books
This idea is simple, if I put an Enchanted Book with Bane of Arthropods into a Chiseled Bookshelf near an Enchanting Table, then the Enchanting Table will not generate enchantments which include Bane of Arthropods.
First, it's unintuitive. Even if a player knew that chiseled bookshelves affected enchanting, they'd expect the opposite of this suggestion — that putting an enchanted book in a bookshelf would increase the chance of getting that enchantment.
Second, I think this would make it too easy to get the enchantments you want. For example, here's a way to get an enchanted book for every enchantment.
Enchant a book.
Put the book in the chiseled bookshelf.
Repeat. Since previously generated enchantments are in a chiseled bookshelf, every book you get will have new enchantments.
Eventually, you'd have every enchantment in book form with not that much XP cost, which would allow you to get any enchanted book you want (except Frost Walker & Mending) by controlling what's in the bookshelves.
I agree that enchanting is too RNG-heavy, but I don't think this is a good way to solve that issue.
The first issue can be solved by giving Chiseled Bookshelves a tooltip, or a different name ("Anti-magical bookshelves"?), or the first time the player obtains a Chiseled Bookshelf, they are rewarded with a written book telling how to use it.
The second "issue" is intended behavior. I think this is a good way to solve the issue of enchanting being too RNG heavy.
True, a tooltip or tutorial hint (those notifications in the top right when you start your first world) would help communicate the purpose. It still seems like odd behavior, but at least it can be communicated to the player.
But to me, reducing enchantment RNG this way seems rather boring and easy. No exploration involved, no combat involved, none of that. Just get some books and spam the 1-level option in the enchanting table until you can control precisely what enchantments you get and thus make a god sword in no time. I guess we'll have to agree to disagree here.