Because books are not made in a vacuum Because you must pay the author
Because you must pay the editor who works with the author
And the Managing Editor and copyeditor who work with the editor
And the designer for their services
And sometimes the outside artist for THEIR services
And don't forget the publicists and the marketing department
And the money that goes into their plans to put the book out there
Or the production department, who must work with paper/binding/trim size/the plants
(Did I mention plant costs?)
(Or even all the silly little costs involved in keeping a business going?)
Books cost a lot of money to produce if you're in the business to produce them well. The stance of Random House is now, I believe, that ebooks are just another format of the books they've bought the rights to, much like a paperback is a different form of a hardcover. I'm not going to really get into that particular tangled web, but I did want to mention that their logic actually makes sense to me, knowing that the text and design from the hardcover is flowed into paperback, and the same is done when it comes to creating an ebook file. Do you guys consider an ebook a "book"? Yes, there are no printing costs, but there is still labor involved and author advances to be earned out. Hence why $9.99 for an ebook and authors going to secondary sources/publishers for their ebook publications are sending publishers into a tailspin of panic. They're trying to regain control of the market right now before they find themselves in a world of hurt in the future if/when ebooks do become the norm. In reality, the ebook market still isn't really being driven by consumers--it's being driven by retailers like Amazon and B&N, who are trying to control the market and flow as much revenue into their digital reading devices as humanly possible.
That said, the above is me talking as someone who works in the industry and understands how bad things could get. As an author Random House's recent moves don't really affect me or anyone who has been published within the last ten years...
If you're interested in reading more, Richard Curtis has a great post.
P.S. I also worry that if lower prices like $9.99 and $12 for hardcovers stick, it might mean lower advances for authors as the amount of books sold might not necessarily go up and/or fewer books being produced each year.