In a perfect world,where everyone was treated fairly, the sun shone everyday and we acheived World Peace, then ability to fly would be based purely on a sound medical and last check ride, not on age.
However...
Surely the whole point of a fixed retirement age is to retire pilots whist they are still fit and competant so as to avoid pilots flying whilst unfit and incompetant until they finally failed medicals / check rides. One-size-fits-all isn't perfect but is the best compromise out there.
You've earned your retirement, enjoy it and hand over control to the next generation.
