This is one of the reasons why I have high hopes that the "Single" format--short e-books at lower prices--might free authors from the shackles of publishing conventions. I've happily paid $5 for The Rent is too Damn High ,The Great Stagnation, Launching the Innovation Renaissance and Race Against the Machine in the last two years, and felt like each was just the right length (and price). In contrast, Future Perfect, which I just finished, while interesting, seemed to go on forever, and I couldn't wait for it to end.
I don't read a lot of fiction, but I have found a number of the novels that I've read to not provide a satisfying return on the temporal investment required for their consumption. Ian Mcewan has a piece in The New Yorker making essentially the same point, advocating for more novellas in the world:
I believe the novella is the perfect form of prose fiction. It is the beautiful daughter of a rambling, bloated ill-shaven giant (but a giant who’s a genius on his best days).I'm hopeful that the rise of e-books and self-publishing are powerful forces to aid this transition, and that many of the 400 page books priced at $30 will be replaced by slim volumes at lower prices. I think that this would be a victory for both art and markets.