I was just watching a cool video on "world gen modders" where the author demonstrated by tweaking just a few values in a custom JSON it was possible to create new kinds of landscapes. At least in their corner it seems like the JSON files are exactly what they want to use to achieve their goals.

It was like that when it was in Java, too. Just tweak just a few values in a custom Java class. Plus you could be as weird as you wanted instead of limited to a very rigid format. You weren't limited to tweaking values.

You can still override it in Java code instead of tweaking values, but it's much more painful because all the existing code is geared towards reading the tweakable values.