With shorter books you have the option to string them together in a series (even when together they'd technically make a standalone novel), effectively making one book into two to four episodes. In this way books begin to resemble TV series, and we can get our reading fix in just a few hours. I had this idea a long time ago, but for a different reason. People don't have the time to read long books. We're used to getting our entertainment packaged into a few hours, not days. TV, the internet, movies, and most of all cell phones, have trained us to have short attention spans. Between that and the obvious economic benefits to the writer, I suspect that the era of long books is now passing us by. In the future it's going to be hard to find long, epic novels. Instead we're going to see novellas strung together in series, with each installment sold for 99c, and each of them conveniently ending on a cliffhanger that leaves you wanting more.
A great example of this is a series I've recently been reading by a fellow indie writer, Isaac Hooke. He wrote the first book in the Forever Gate series at just 86 pages. At first, when I saw this, I thought it seemed like a cheap shot to the readers. I thought no one would pay 99c for a short novel, but when I read Isaac's debut, I realized just how effective that length was. It was a great, fast read--never boring, never slow. Forever Gate had my attention from the first page straight through to the last, and whatever depth I felt was missing, I later found in the sequel. If anything, the shorter length only left me wanting more and made me more willing to buy the sequel. Overall, this was a brilliant business strategy, but also in my opinion, a better way to write a book.
Check it out for yourself: Forever Gate (Part One) Kindle Edition, by Isaac Hooke