Yeah this +1.
It would be good for and interesting for players unfamilar with the lore of the forgotten realms. History like the fall of the Tieflings to the 9 hells and the netherese etc. would be an interesting read for many player and personally love that shit as it quite literally world building.
I mean Larian could just copy most of the bestiary from the player handbook wouldn't be too much trouble I wouldn't think.
Exactly, that's the reason why I thought if it. The codex would be helpful for new players that are interested in the lore of Dungeons and Dragons. It can also give regular players an idea of what has been happening around the world in the game.