I actually think that XML has some of the best tooling in the entire industry. The problem is: It's mostly commercial tooling, which costs money. Stuff like Oxygen or XMetaL is pretty neat, and I always found Visual Studio's "Create Web Client from SOAP" pretty useful (especially if the Web Service is written in .NET, since it auto-generates a proper WSDL file).

XML is all about tooling, but most FOSS folks insist in holding it wrong, editing XML files in vim/emacs.

I find XML tool in general feature complete and great.

Especially editor integration works great as opposed to YAML which is so ambiguous that it IntelliJ IDEA constantly breaks indentation during copy and paste.

And better conceptual docs because it's supposed to be that elements are complete deserializable objects. Having to resort to xpath as the default way of poking at XML where JSON has a good implicit default schema made XML feel so clunky.