I'm the author of the ASHFALL three-and-a-half-ology: ASHFALL, ASHEN WINTER, SUNRISE, and DARLA'S STORY.
Holding hardcovers can be exhausting.
Why just curl up with a good book, when your book can curl up with you, too?
From http://www.epicreads.com/blog/10-reasons-why-paperbacks-rule/