I think this would be nice. I can't help but think of Dragon Age's codex system, where finding books (Or otherwise stumbling across information, such as with first-hand experience) filled in a codex of lore you could look up at any time. It'd be nice for my character to have a tome all about the mysteries of Eorzea.

Oh gods... if this isn't added in-game, I am going to need to do this with a blog.