JSON vs. XML is largely irrelevant IMO. What is needed is something with as little extra crap as possible so that it is possible for a developer and/or diff tool figure out what is going on with the file.
The only real relevant part is that this means no comments. So if you DO decide to do something neat in your build files, you can't note anything about it. Or easily remove pieces for testing.
But it's JSON which is so hip instead of XML which is so bloated. /s
But it's JSON which is so hip instead of XML which is so bloated. /s