Think about it:
When an agent sells your book to a publisher, all the expense of producing your book—editing, interior design and layout, cover design—falls on the house. Then they pay the author an advance—more money out. If you’re lucky, you get some marketing attention from the publicity department, again at their cost. This investment on their part is, of course, with the expectation that your book will delight readers to the tune of earning back their gamble and more.
Imagine now the wheels turning in the minds of those running the publishing houses.
What if we could offer what CreateSpace or Lulu does, leave the control in the hands of the writer (which is a huge benefit of self-publishing), and reap some of the profit?