The story of the DC-10 proves that even with the best intentions, unexpected failure modes can cripple mechanical and hydraulic systems in unforeseen ways, which is why I get so frustrated when people assert that such things did not happen before the advent of computer control in transport-category aircraft.
I understand your frustration. I'm only speculating like Taleb, that may be human beings are not good at predicting/dealing with the kinds of nonlinear failure modes exhibited by digital systems.
And when they do fail they are designed to fail gracefully. In the case of a severe failure they will do exactly as many demand, which is to hand control back to the pilots in the form of Direct Law.
Maybe my definition of graceful degradation is different from that of the system in question. We may know more details tomorrow, but the picture ACARS paint of how the system degraded is anything but graceful.