With that said, it’s not that we won’t be doing it in the future, it just won't be right away.
They will be doing something about the drop rate, just not right now.

In short, the amount of tomestones of mythology players can receive will increase to maintain overall game balance, rather than simply reducing the cost of the books.
What I'm taking from this statement is that they will be increasing myths received in order for new players to catch up faster, not necessarily to address the atma/animus grind. Being able to acquire the books is just a side effect.