PJ2
I do see your point - a warning vice "circumstantial evidence" so to speak, would probably stop action and cause a change in behaviour but then the question becomes, At what point do we stop designing for such things?
We never will stop designing for such things, we are on that path and no rationale will stop it. The question will only be how quick it will be done. And i fear, the new generation of pilots / system managers does not want anything back from the past and will accept any gadget which releaves some workload and some asociated necessary training. I´m not saying that it makes me feel safer as a pax in airtravel.
The problem lies not in the difficult tasks which have to be fullfilled routinly, but in the onetime ones, which we still leave the pilots to do. But with limited knowledge and no training (knowledge and training developes expierience) even simple tasks can lead to desaster.
Back to the AP: If that one is forced off due to mechanical loads or any not computable malfunction, then be it. But when it is deliberately switched off by the system after thorough evaluation of its inputs in straight and level flight a courtesy warning prior drop off should be not too hard and expensive to design and implement. It´s just that nobody thought about it until now.