You know what is an even better way to provide incentive to read those books? Have quests linked to those books.
Oh wait, my bad, Larian already does that.
That's fair; I meant the minor books that don't really do anything other than add flavour to the game setting (like the examples from my OP).
Dragon Age gives you reward xp for finding books, not reading them. Other then that its not a bad idea.
True, but those books (or well codexes) are usually like one page long, so finding them more or less equals reading them. Either way, it would be a nice bonus if something happened when you picked up a random book and flipped through it. ^^