If Airlines had enough resilience to produce manual flight plans would this have reduced their own impact. And reputation hit.
Depending heavily on an automated system with little back up and resilience down to aggressively minimum levels really doesnt seem to make much sense.
Suppose finger pointing at NATs in a blame game post event would be about the only defence Airlines would have if they were inept enough to have little resilience.
No automated system is infallible. Its unlikely it ever will be either.