> XML's saving grace was that it came with good schemas out of the box, so turning something from XML to, say, a Java object, was not very difficult.

Huh? How do you know what types <a><b c="d"><e/></b><b f="g" /><a> has? How do you transform that into a Java object? For that matter, if you manage to turn this into a Java object, how do you know how to transform it back into XML? What members turn into attributes and which turn into sub-elements?

Or are you referring to XSD, which showed up years later, is not required, and often not used? Yes, XSD grafts typing onto XML quite effectively, but this is a bolt-on just like the JSON approaches. It just turned out to be a widely-adopted bolt-on.