I think a lot of gamedevs assume that the "art" and "music" part of their game is just, making the art and music. But art direction and sound direction are their own separate skills. Original assets have their own flair and flavor, that's definitely worth something. But it's very easy for a game with public domain or stolen assets and a strong sense of direction to feel more aesthetically vibrant than a game with all original assets and staid, boring direction.
I think even artists and composers would benefit from projects where they use other people's art/music. When you're collaging, the direction stuff is way more fore-fronted and obvious, because the assets don't speak for themselves the same way. I think programmers benefit the same way from using higher level engine tools like rpgmaker or ren'py. It's good to sometimes set aside the stuff you're already good at and focus on other parts of the expressive language you're working in.