If operating experience shows 1% too high fuel burn or .5% too low dispatch reliability, something is changed.
If operating feedback from pilots identifies weak points of the aircraft or built in traps, maybe the pilot training is improved, but nobody would improve the aircraft until some serious incident results in according official safety recommendations.
Same applies for feedback from maintenance.
Aviation has always relied on in-service feedback, but this element is quickly fading away as nobody listens to pilots or mechanics any more, and management only worries about economic aspects.
True words nowadays - I 100% agree! Thank you, Volume!