The Library in "The Library of Babel" is a universe built according to a set of rules. In fact, it's the most orderly universe you could possibly imagine. All of the rooms look exactly the same, and contain the same number of books with the same number of pages. And the way the people of the library think about things is extremely orderly as well – just look at the arguments that the narrator presents to us. Notice how they're extremely logical and follow a clearly regimented system of thought? The orderly reasoning of the Library's inhabitants allows them to come up with the greatest rule of all: the Library is "total," meaning it contains every single combination of letters that is possible.
The orderly structure to the narrator's writing has its roots in the ordered structure of the Library itself. The narrator takes the visible order of the world he lives in as a starting point, and from there uses logic to make other assertions about the Library.
Instead of setting off on dangerous pilgrimages in search of meaningful books, it would make a lot more sense for each librarian to read all of the books in his own native hexagons.