>Take a step back and think about why pollution on Earth is bad, and you'll realize that "polluting" an asteroid isn't ethically wrong.
Of course, that only applies as long as those asteroids are utterly devoid of life. Once there's an ecosystem, polluting becomes ethically wrong again.
Why? There is no ecosystem on top of Everest yet people will get upset when they see what it looks like.
I think in the vast majority of cases it is an ethical concern, but I agree that even in the absence of ethics there is an aesthetic dimension. Usually we rephrase it under the umbrella of "preserving it for future generations"
Of course, that only applies as long as those asteroids are utterly devoid of life. Once there's an ecosystem, polluting becomes ethically wrong again.
Why? There is no ecosystem on top of Everest yet people will get upset when they see what it looks like.
This is an aesthetic decision, not a moral one.