Here's one example of why positive longitudinal stability is pretty important
:
Falcon 900B accident
Crew: Fatalities: 0 / Occupants: 3
Passengers: Fatalities: 7 / Occupants: 10
Total: Fatalities: 7 / Occupants: 13
....
Between FL150 and FL140, for approximately 24 seconds, the aircraft experienced 10 oscillations in pitch axis which exceeded the limit manoeuvring load factor. Maximum recorded values were: +4.7 g and -3:26 g.
....
CAUSAL FACTORS:
1. Inadequate risk assessments of the PITCH FEEL malfunctions.
2. Overriding of the A/P on the pitch channel by the crew.
3. Inappropriate inputs on the control column at high speed and with Arthur unit failed in 'low-speed' mode leading to Pilot Induced Oscillations.
4. Seat-belts not fastened during descent flight phase.
They didn't even have no feel; they just had reduced feel, and it rendered the aircraft all-but uncontrollable in pitch.