I think main problem people trying to solve is treating JSON as computer-human interface. It was not designed for it and I don’t think we need to expand its use-case. You can perfectly use subset of YAML with much better readability for human interactions. I wrote custom parsers for subset I need with like 100 lines of Python code. JSON should stay as a loggable system-to-system format that you can render in a more readable way.
JSON is pretty close and much more widely used/available. It's fine.
Actually, right this moment I am writing docs for my mini-yaml to generate JSON Schema Draft 4 for our EDA. Easy-peasy