If you replace "Pkl" with "XML", this is all exactly true for XML. Ten years ago we were generating C# classes, typed validators, and automatic parsers from XSD schemas, with automatic IDE integration and IntelliSense completions when editing the XML documents--is this just XSD for the younger JSON generation? I shipped multiple megabytes of complex manually-written XML configuration this way and it was delightful. We never would have pulled it off without XSD.
What you're expressing here is that many of the ideas from that period of xml-centricity were quite good and useful!
But xml itself was not a good language for this, because its legibility is terrible. It's just not a good format for human reading and editing. (But it also isn't a great format for machine interaction either...)
So yeah, I see it as a good thing that this seems to be able to do all that useful stuff you were doing with xml and xsd a decade (and more) ago. But it's (IMO) a much nicer way to do it.
