It's true that JSON document databases very closely follow the model set out by earlier XML document databases, and have succeeded for the reason Yegge spelled out.
The big lack is the equivalent of XQuery and XPath, in my opinion. Javascript plays this role in some systems, but I don't think there is anything for Javascript matching the power and flexibility of XQuery/XPath for querying and transforming data.
I would be happy to learn about query languages for JSON document databases that prove me wrong.
JSON is traditional: dictionaries, arrays. OO languages have built-in syntax to deal with those, via [] and dot notation, and the array objects nowadays have ways to do map() apply() grep() etc. on the collections.
The main thing missing is that XML has attributes, so you can query against those.
I won't say that the JS stuff is better, but it's one less thing to learn, and what you learn is directly applicable to writing apps in JS.
The big lack is the equivalent of XQuery and XPath, in my opinion. Javascript plays this role in some systems, but I don't think there is anything for Javascript matching the power and flexibility of XQuery/XPath for querying and transforming data.
I would be happy to learn about query languages for JSON document databases that prove me wrong.