You are really right. As a collector of old Blade Runner stuff, some of the spin off books and magazines about that 1982 film used to go for hundreds of dollars. Last time I looked, they weren't even close to that.
There was a time in my life when on short notice I had to move from a decent two bedroom apartment to find any place that would allow me to have a large dog, and ended up moving to a one bedroom studio. I had to get rid of half of everything I owned, including a massive amount of books (donated to the local library).
As I get older, too much "stuff" becomes a pain. I still have way too many books, even though I went through that process again last year and got rid of about 300 books.
I do feel that culturally we are losing something. But maybe every generation feels that as we grow older. But I don't see the great literary authors or the reverence for great books and authors of the past (or even modern, still-living authors). Pristine first editions of books written in the 80s by prestigious authors are going for about their 1980s cover price. It blows my mind.
Your post is really interesting, though. I want to think about that trend you are pinpointing. There's something to it.