Comment by RightWingRabble

We subconsciously equate size with value. A physical book sitting on a shelf benefits from being (or looking) large, especially if it costs $15. Digital books don't suffer from the misconception and lots of independently written books are shorter than those intended for print. That's my perception, anyway. I'd be curious to see hard numbers comparing book sizes between those intended for print and those that are e-book only.