If you're late for a flight, and miss it, and there's one departing immediately, you can't just 'hand' over your e-ticket info at the counter. Your ticket must be reissued to reflect the next travel date/time, even though its the next flight. With a paper ticket, the check-in agent will just take the ticket and put you on the next flight - great if you have say 5 mins to spare only. Otherwise with an e-ticket you will be sent back to the ticketing counter and get it reissued but it does not count as a reroute reissue so no fee is involved (officially)... up to the individual airline if they want to charge you for their efforts or not.