I mean. Traditional systems go through a LOT of very rigorous and documented-ish processes to be reused (not quite Rocket of Theseus but…). They are expected to be unusable after a launch and being able to reuse them is kind of an added bonus.

Reusable systems are specifically designed to be… reused. So if they aren’t reusable after a launch, something went horribly wrong and we need to understand why. Because maybe we got lucky and the proverbial door fell off after landing this time. Maybe next time it falls off mid-flight.