That is the public's fault - always looking for the super deal on the airfare, and perhaps not being willing to actually pay the real cost of crewing the flight.
Nope...that's a failure of capitalism as posted above. Legislation should have prevented this, just as it should have prevented the worst excesses of the finance industry.
That's a lesson we (humanity) have yet to learn and probably never will. But don't obfuscate it, by pointing the finger at Joe Public, so as absolving aviation.