If DL doesn't want it's most loyal, tech-savvy and experienced customers blowing up the phone lines then how about allowing those of us with RUC's and GUC's applied to rebook ourselves by doing one of two things automatically when a flight gets cancelled on day of departure...
1. Immediately re-deposit the certificate and let us rebook using our paid fare class.
OR
2. Immediately re-ticket into the class of our seat assignment so we can rebook from there. If DL considers this to be such an "upgrade" or enhancement, then only give it for certain purchased fare classes or status of the traveler.

They can't really automate the application of these certificates, but they can, and already have the ability, to automate redeposit or reticketing into the upgraded "classic" fare class.