If you're looking for automation failures to cite as examples of when human flight crew, in the pointy end, become invaluable, surely the numerous A320 electrical failures which have disabled most of the flying displays and other electronics - including the radios and transponder, leaving the acft incommunicado with the outside world, would do? Remember that these were faults that "couldn't happen", with current generation technology.. It's no good having 1, 10 or 10,000 pilots trying to control an aeroplane from the ground if the computer in the air has shut up shop without warning and gone for lunch.
And this is not a hypothetical failure situation. It has happened. It will happen again. It's one thing playing this game with spy planes over unpopulated areas, quite another with fare paying pax over a population.
I suspect, though, that pilotless airliners will happen, sooner or later. And we'll learn the hard way.