Paper tickets were great until you got 4 books of tickets (or more) as part of a huge trip. Their bulk and security was painful.

Even more painful was my experience after keeping my tickets and passport in the Oz Govt supplied plastic wallet on a trip in hot and humid Asia - only to discover a pulpy mess where rain, sweat and heat had made the tickets unreadable and impossible to open up.

E tickets are far more convenient but I miss the paper books as they were great souvenirs.