I understand the history of why change fees are in place. (Combination of 1) ensuring that people actually show up for the flight and 2) paying for the administrative fee to rewrite a ticket)
Southwest, as well as other low cost carriers, don't charge a change fee, and non-refundable tickets retain their full value toward future travel.
The administrative fee is almost non-existent now, as most transactions are electronic.
So what would happen if the legacies dropped all change fees? Do airlines count on those fees for the bottom line in a significant way? Would the price of the ticket, by definition, have to increase (no more "super saver" fares?) Would the "no show" rate increase to the rate that airlines will have no way to track yields?