Famines and disease were also much more common prior to the late 20th century. If our progress regressed it would still be cause for concern, even if the status quo hasn't lasted so long.
If we go back to 20% literacy, we still have to likes of Tolstoy.
Arguably famine and disease are bad for those who experience them. Replacing reading books with blogs, games, and video? Not quite so clear.
I argue that nothing is lost at all. The bookworms (to which, I hope, I belong) shouldn't be said if 90% don't participate in their favorite hobby.