> it's sometimes "you can't possibly fix the bug or implement the feature that you want to"

Yes. It is, and that is what any responsible person should choose.

So you'd tell customers "No, I'm not fixing that bug because doing so would offend my aesthetic sensibilities. Yes, I know you have a support contract, but I simply refuse to address your problem even though I could"? Or maybe you'd phrase it a little differently in public.