The pages of my book are un-evenly bound and look pretty ragged. Why?
The type of binding your are referring to is intentional, and called "deckled" edges. They are common and even desirable, to make the books look old and more valuable. Until the 19th Century all books were printed this way on hand-made paper. See John's response to a similar question here.
Here's an example of "deckle edge" paper