Yes, I think this is a good thing. I know since I started using a not nook/kindle personal media device to read books, Ive read more books in the last 2 years than the last 20 (I hate physical books)
As for the notion of knowledge lost due to an apocalypse. The notions of EMP discharge are greatly over exaggerated in that theres still going to be plenty of non shielded devices that survive. Also, its not difficult to make a Faraday box case to help further shield the device if your really that worried that your copy of World War Z isnt going to make it through the apocalypse. Seriously, hardshell case lined with heavy duty aluminum then coated with rubber is enough to "ruggedize" a box to shield against EMP. But the point is... I think you have to worry about hell fire more than the EMP. Also, after something like that happens, are you really going to have time to sit around reading? Wont your time be consumed more with ... Hunting, finding clean water, avoiding looters/raiders, staving off radiation poisoning, defending against super mutants, and any of the other promised pitfalls of a post apocalyptic world.
Anyway, glad to hear people are reading, and yes this is one form of digital distribution I can honestly get behind.