I think it is good to require quotation marks for strings, at least for values (although I could live with it if quotation marks for strings are allowed even if not required, since then, if you do not like the feature of not having quotation marks for strings, you can just not use that feature).

Maybe it would be sense if quotation marks were not required for keys with only a restricted character set which are not an empty string, though.

It’s also a lot less obvious. What’s so difficult about wrapping a string in double quotes?

It’s easier until you hit one of the cases where a particular value is interpreted as a different type, possibly in a very confusing context. I’ve seen that bite enough people that I end up quoting strings to avoid confusion.