Closing tags is not really an issue with XML.

In my experience, the biggest reason people hate it is because it has too many ways of structuring data, and it allows people who design the schemas to go overboard. Attributes or child nodes? Multiple namespaces or just extend the one you have? CDATA or embedding?

That said, simple XML is as good as simple JSON. XML is fine if you keep it simple when designing the schema. AND of course one can screw up with JSON too. But after almost 20 years of people over-engineering their XML schemas, I can't fault anyone for choosing a simpler data format.