It's not necessary at all in any manner but maybe later on it would be cool to have a book vendor like there was in Oblivion. The bookstore was called the "First Edition". The idea is that when you buy books they are consumed via your inventory similarly to motifs and are sent to your eidetic memory. Could be a decent piece of distraction content for some players and help liven up the world a bit. The Imperial marketplace was always a cool place to loiter in Oblivion.

More shopping options would be cool.