What's changed is the search/indexing - it used to be really painful to crawl around used bookshops until finally I found one that had the book I wanted. Now I just go online, type in the name and the book is there. Sure, the post office make more than the seller does from the sale, but the buyer saves a bundle.
What we are losing is the "box of books for a buck" random introductions to new authors. Of course, that never made the authors a cent so they probably don't miss it
And these days we get blogs and forums like this one instead. Which is better I think.
Again, this further devalues ebooks - I can't legally sell them once I've read them. The author can no doubt argue that the resale value is now almost nothing so i haven't lost much...