If you coded your program in JS, I understand that you might be inclined to use JSON. Maybe you want to reduce bloat or dependency by not including a TOML or YAML parser. But you are making it more difficult for us to contribute to your project, or fix something on our end.
It is quiet old too. Probably older than time itself given that it doesn't support date standards ISO 8601 or RFC 3339 out-of-the-box. That is because it doesn't need to, because it is not for configurations or manifests.
