The autopilot turning off altogether is the biggest equipment problem here (along with averaging/independent sticks). An alarm will surely be necessary but I don't see how killing off autopilot helps since the pilots probably won't have any better of an idea. Perhaps this specific incident caught an ugly edge case.

There is actually a fair amount of ergonomics and interfaces design that goes into these systems - at least equal to Amazon's shopping cart, probably more. Same goes for systems like ATC.

"Stall" does mean "dive now" to every pilot. It is extremely questionable whether including this information explicitly would help at all in the chaotic, confused environment in the cockpit at the time. "Why are you pulling the stick back" is way too long as well, although it does raise a fair point about keeping both pilots aware of each other's control inputs.