As long as you give the skilled pilots the feeling they do better than the less skilled and the other way around I really have no problem with the concept.

Let the medals untouched and give them a "minimum qualification" that unlocks the next race. Give the advanced players more reward, it has to be visible that you mastered the game on easy or hard.
This way not only the skilled pilots feel satisfied but also the noobs feel like "hey, wait, there's more to get when I play with hard difficulty!".
More concept ships for example. Or more images in the gallery (yes you would have to add one again ) and maybe even more game settings for the people who master the game on a higher difficulty level (make races available with custom number of laps for example).
Stuff like that.
So noobs are interested in playing more of the game and the skilled people are happy with what they get and they see that they are good.

In Pulse you just get a small info on the screen that tells you if you raced in hard or in easy mode. That's all.

And it should clearly visible that there are different difficulty settings available. If I didn't know it was in, I probably had not seen it.
Remember: not everyone reads the manual.