Do you plan on keeping the car or selling it?
If the guy who hit you is footing the bill, I would repaint. If you sell at 100k miles no one will care, however if you plan on selling at 40k miles you need to think about it. I personally would want the bumper to be scratch free and wouldn't bother thinking about what some hypothetical buyer in the future will want. If you think it is that big of an issue, take some pictures to prove to a buyer that there was no big accident, you just pamper the car and keep it scratch free.
