Hello Hanoijane,
So you have 'sat' in a Mig 21. Wow!
But have you flown one? Better still, have you flown one in combat? The whole reason for reclining a combat pilot is to enhance his G threshold.
Possible the weak link in any air superiority fight is the man who drives it. Increase his G threshold and the fighter can be made to turn better.
Many years ago a fighter was designed with the pilot actually lying on his stomach. Perhaps that was not a brilliant idea, but it did enhance his G tolerence
Sadly for us pilots, future combat aircraft will be pilotless.