My video game collection is over 20 years in the making. I would give up fingers and toes before I give up that collection. It is precious, and dear to me. I also think that, especially with modern games, going entirely digital would be a real hassle. When games are over 15GB, and potentially up to 50GB a piece, keeping them all on a hard drive is quickly going to eat away at your space.
That being said, music does not have the same issue. And neither do books. Both have very small file sizes, and I love having an MP3 player with hundreds of albums on it. I also love my kindle, which has hundreds of books on it. This is convenient for me; but I can see why people who feel the same about their books and music collections as I do about my game collection would have conflicting feelings.
One more thing I'll add, is that I love some of the features digitizing books gives access too. I love that I can share quotes to my social media networks on my kindle, save highlights of a book for later viewing, and look up a word I am unfamiliar with without getting out a dictionary or my cellphone. I'm also a sucker for progress bars, seeing how far I am in a book.