In my mind the change happened long before e-Readers came along.

Even in the 1980s there was a surge in expensive "trade paperbacks" that were frequently terribly built. Like you buy one from the store and open it and the binding cracks the very first time.

I have a lot of mass market paperbacks that I mostly bought used in the 1980 and I'd say in the 2000s they were in mostly excellent condition, but at this point in time they are pretty yellowed. My storage conditions are awful, an old farmhouse with a permeable basement, but when I look at books of all kind from the 1960s and 1970s, especially mass market paperbacks that have been rebound, the yellowing is severe.

But even despite them being "cheap", "low quality", etc. I think they were mass produced and more consistent in quality than many more expensive books.

I buy a lot of e-Books but I am putting together a kit for doing tarot readings for other people (most people find the cards are cooperative 30-50% of the time but I have a shtick that gets a response I like almost 100%) and I am starting to be able to work without a book but I still want books and for that I want real books, small books, not something to look at on a phone or tablet.