> I just hear my coworkers always lambasting that API provider for their usage of XML

I hear this too, but often when I ask why people say things like that, it's either because XML is "outdated" or because they don't like it.

It's like programs written in C or C++: very few large projects chose those languages nowadays, often for good reasons, so the projects written in those languages are usually 10 to 20 years old. Age comes with a lot of legacy cruft and obscure behaviour, but that's not the fault of those languages per se. Or for people blasting banks for using COBOL, even though COBOL is a perfectly fine high-performance language for the niches bank mainframes serve.