"And yes, it will always be better to have a paper book of 900 pages than a big pdf file to read in a screen."
That's entirely a matter of habbits and opinion. If you just want to go read your book on the beach sipping your drink and look like in a movie.. well, you have no other choice.
If you want to search trough books concerning your probmlem at hand, WHY would you have to get up from the computer and start flipping pages if instead you could enter a search and have the references list of WHOLE LIBRARY!!!
I would say there are (still) SOME uses for books printed on paper but I would be brave enough to say, that most of them are "historical" or traditional nature. Books on paper will be something you will see only in museums in 50..100 or so years, when everything will be digitized and recallable on devices with more convinient user interfaces.
Even today books are printed "on demand".. which already tells me that it's a thing of a convinence, not necessity.
Programmers should be first to drop this aristrocratic abstraction of information as "books" and start seeing well packaged chunks of "the flow", "learning sessions", "verbal experience" or whatever is suitable according to content. I understand this is a paradigm shift that will not be well accepted until generation (or two) changes.
This does not stop programmers as technologycally un-challenged people to adopt such attitude YESTERDAY.
Or as your article already kind of confirmed, they mostly have done this in one way or another.
So this is "A Good Thing"(tm). Programming books are prime candidate for trying out digital distribution models, go with it! And take your publisher on the ride with you.Then complain that sales have dropped.
Right now your article mostly says:"Look, I'm cool the old way! And you should be too, because... emm.. ojeah! reading stuff on the computer display is shit!!"
My proposal: buy a better monitor. It probably costs only 2..3x more you paid for your current crap.