I think what happened is that people building a complex system, who knew they needed schema etc would just use the XML&#x2F;ws-* ecosystem, because as repugnant as some might feel it is, it is all written, debugged and works. If people didn&#x27;t need complexity, they used JSON.<p>The XML option kept complexity out of JSON.<p>However, its inevitable people starting with simple systems (using JSON) would <i>become</i> complex - perhaps partly due to dramtic success. And converting everything to XML would be time-consuming and error-prone and... repugnant. So. This is where the demand for json-schema comes from. And it does seem inevitable: the inertia of back-compatibility is one of the more predictable features of software.<p>I can make the hopeful observation that things aren&#x27;t quite as bad as the cynic take above: people <i>do</i> learn from some of the mistakes of previous technologies. There is <i>some</i> progress.<p>I dislike JSON-schema because it&#x27;s like a JSON version of XML schema. I think a simpler scheam would better serve JSON and its typical uses.<p>Is your &quot;lightweight schema&quot; a simple schema written in json-schema? Or written in a lightweight schema language?