sometimes people fall in love with quilts in books and want a kit for them- once you buy the book you do not want to re-buy the book every time you are going to make a quilt from that book- what if it had 60 quilts in it? you might want to buy 60 fabric kits- but 60 copies of the same book- because you want it included in every kit?
usually if the pattern is just that- 1 pattern it is included with kits- if it is a pattern from a book or a magazine you have to purchase it separately.