Various observations come to mind:
1. Someone somewhere, perhaps, signed off on NOT installing a correct, suitable worse case, thoroughly tested - often- backup system. Heads might roll, but don't hold your breath. They can not pin 'pilot error' on this one.
2. Someone somewhere did not do a thorough threat/risk assessment of 'what happens if...../'
3. Someone somewhere was being over complacent. "it has never been a problem before, therefore it's OK."
4. When volcanic ash shutdowns airspace, and puts a/c & crews where you did not plan them to be, you used your computer systems to sort out the consequential poo-pile. Oops, the poo-pile is caused by your own computer system. Now where is that pencil & rubber, slide-rule and abacus? What do you mean there's no paper back up? Oops.
This saga could go on long enough for Hollywood to make an epic drama out of it, at least a TV box set. Then you could throw in some foreign espionage conspiracy and ruin the whole truth. Ground Crash Investigation could have a field day with this one. Human error puts a company on the edge.
What will be interesting will be the investigation as to root cause. I wonder if that will ever see the light of day to the public. Check out the dole queue for a clue.