Games are a medium that combine many different aspects, including narrative. I shouldn't have to pick between shooting things and learning interesting things about the gameworld if it's done well. Secondly, putting the Grimoire cards outside of the game was a horrible mistake, and they should have placed in an in-game menu which your ghost can read it to you, much like Mass Effect's in-game Codex. Thirdly, the game barely gives us a hint that this lore even exists, so even players that want to learn the lore may not even know to find it.