But why would it matter if you are never going to see the scratched surface? I could give you two iPhones already in cases. They could be identical aside from one being scratched to hell under the case and the other being pristine. Would you know the difference without taking the case off? Since you are a case user you never have your case off anyway so you would never know if it is scratched or not.
It would matter to ME. I don't want any scratches on my iPhone. Period. Even if it is kept in a case. Sorry that I can't explain it better.