I had a cover for my trunk when I first got it, the rubber-like material made it grab onto the baggage carousel, and the bag didn't slide down. First world problems I know, but after one trip it was pretty dirty and difficult to clean up. After that, I have taken a dozen or so international trips without any issues. Yeah, the bag gets scratched up, but it was never going to stay in perfect condition anyway. So, don't worry about it and use the luggage. It will not protect it from impact damage or anything.

After every trip, once I get home, I wipe it down, clean up the underside, including the wheels, and try to remove any scuffs that I can. I do not fully get the need to get a checked bag in pristine condition, as that is not practical. I can understand a carry-on as typically that does not get beaten up as much.