Rigidity and consistency are not always bad things. They can help prevent bugs, security vulnerabilities, and they drastically reduce complexity of implementation.
JSON might often be too rigid, but I think it's important to note that "easier" (in that you don't need to learn the syntax) isn't always better.
This "easier" format is actually more "complex". JSON can be described with just a couple of simple rules (http://json.org/ ), while this format adds many new rules (e.g. for doing same things in multiple ways). The more rules you have, the more things you have to remember, the harder it is to find the reason of the problem.
BTW. it is very simple to do comments in JSON :) You can just add
"comment1" : "This is my comment",
to any object, it will be ignored by software that processes your file.
JSON might often be too rigid, but I think it's important to note that "easier" (in that you don't need to learn the syntax) isn't always better.