It’s an improvement because it’s a public contract that can be enforced both client(s) and server(s), and a relatively standardized interface format that is par

It’s an improvement because it’s a public contract that can be enforced both client(s) and server(s), and a relatively standardized interface format that is parseable by all manner of tooling. Otherwise, it’s just in your code, where it’s potentially not just “hard-to-read”, but impossible to read for anybody but the authors. That said, I’m partial to other solutions like protobuf, but what can you do.