Machinbird,
Now take that same alternate law aircraft and start with near full deflection roll inputs in cruise and tell me what happens. That is what happened with AF447 and QZ8501. In both cases, it not clear that either PF knew from the outset he was in Alternate Law. That is a setup for roll PIO. Do you understand the hazard that roll PIO presents?
With great respect, have you flown an Airbus in Alternate Law? At high altitude?
The transition is seamless, and roll control is not so different to Normal Law. with regard to your first sentence above, I wonder how many pilots have actually manoeuvred their aircraft in
Normal Law at cruise alts? Not many, I bet. And even fewer would have used full deflection roll inputs under those conditions, which gives 15 degrees per second in Normal Law in the Airbus. I believe that the issue is general unfamiliarity with high altitude/high Mach manual flying and reations to upsets than it is about 'degraded' flight controls.
You have it right when you suggest that pilots should be cautious with control inputs in Alternate Law at high altitude, but so they should even in Normal Law. The aircraft will ultimately protect you, but shouldn't be asked to!
Finally, do you actually mean PIO, which has a very specific meaning? I don't believe that either of the accidents in question showed signs of PIO. Maybe some over-controlling in the case of AirAsia.