It's because we can discuss during pages about the nature of a shadow in a roleplaying game 
or debate about the Code... which is in the same game...
That's so fun to read and think about those things in the game, trying to reflect the way of thinking of the era...
I can easily imagine in-character philosophical discussions about the same things, which is fun 
A benefit of a rigorously structured background.
/me imagines the nature of shadows to be pretty far up the Magic Theory ladder of knowledge, not to mention the finer points of the Code being totally lost on more rustic magi.