I think the original article misses the point that paper books compete not just with ebooks but television, the internet, movies, etc. and so publishers have had to find ways to make books more attention-grabbing. I see that with a lot of public domain books that have bright graphics and big pictures on the cover. A couple examples:
http://www.amazon.com/Wuthering-Heig...6605917&sr=8-1 Wuthering Heights
http://www.amazon.com/Northanger-Abb...6605995&sr=1-1 Northanger Abbey
Sorry, I don't know how to better format the links.
The interiors of the books don't innovate in any way and could have been made a hundred years ago, but the exteriors look a lot different from comparable editions of an earlier generation.