This is a critical step towards creating a fully reusable space system where both the ship and the launch vehicle are reusable.
Reusable spacecraft have existed before, but Starship promises a completely different scale: the ability to reuse a giant rocket without building a new one for each launch.
If SpaceX succeeds in establishing a rapid turnover of such devices, the cost of delivering cargo to orbit could drop drastically, and spaceflights would go from expensive disposable pods to regular transport operations.