Disposable on Earth means sitting in a landfill. Disposable in space means burning up in the atmosphere. Ironically by not using disposable equipment you can end up cluttering the space even more because we still need to make advances.

With current space infrastructure, disposable is the only way to go while maintaining progress. As long as the hardware is optimized to fully burn up on re-entry it's acceptable at current scales.

For example, Starlink can keep unit costs low and focus on getting at least some functionality going while simultaneously working on next generation satellites. Since the satellites are somewhat disposable (expected to have an operating life of ~5 years), this approach doesn't lock them into a specific generation of satellites.

Eventually, we'll have enough hardware up there that it'll start being important to try to refurb/recycle, but that is not practical at scale right now, given that we're only starting to seriously explore things like mission extension vehicles, active debris removal, orbital refueling and satellite servicing.

Depends on the application. Starlink satellites are disposable (demisable). Not to say they shouldn't have stationkeeping to prolong the mission lifespan, just that there's no contingency servicing/maintenance plan if something goes wrong. They just return to dust.

When it's millions or billions of items? Sure.