"But at no point in that loop is the pilot involved, nor should he be since he generally doesn't understand the issues and is in no position to decide whether the aircraft is serviceable or not."
Why not!! he is the person who is responsible for the craft, who says he does not or should not be trained to understand at least the basic issues?.
Looking at the graph it would appear to me that there was a significant change in levels at 193, if I was confronted regularly with the typical daily graph & saw this steep increase I would want an explanation & want it before I flew.
It should be possible to produce a daily trend graph that shows the variation from the norm then changes such as that would stand out as an anomaly to be examined