One could say that about all sorts of capabilities in an aircraft that, in normal operation, seems insane. Is there ever a valid reason to fly a cargo plane inverted? See https://en.m.wikipedia.org/wiki/Federal_Express_Flight_705 for the answer.
Airliners are simply not designed to fly inverted. In Tex Johnson's famous barrel roll of a 707, he kept positive g on the airframe at all times.
One problem with flying inverted is the bottom of the airplane tends to accumulate junk - nuts, bolts, dropped tools, lunch boxes, dead mice, etc. Turning the airplane over means all that junk falls into the machinery, potentially jamming it.
Right- in the FedEx case it was a last ditch effort to literally knock the suicidal flight crew member off his balance and regain control of the aircraft. If you have a 'nanny' computer telling you that you're unable to do that, those crewmembers may have ended up dead instead.
Point being, in an unforeseen emergency, allowing crews to override the normal safety mechanisms may in fact save lives.
I guess the question is what's the likelihood of such a situation, vs the likelihood of the situation where a 'nanny' computer prevents the crew doing something dangerous?
The MAX crews had the option to turn off the stab trim. Of the 3 MAX incidents, only one of them turned it off, which is why you only hear about the other 2.
One problem with flying inverted is the bottom of the airplane tends to accumulate junk - nuts, bolts, dropped tools, lunch boxes, dead mice, etc. Turning the airplane over means all that junk falls into the machinery, potentially jamming it.