Besides comments I see none of these as negatives. JSON is plenty readable for most in my experience and there are plenty of great readers/prettifiers for it.

Besides comments I see none of these as negatives. JSON is plenty readable for most in my experience and there are plenty of great readers/prettifiers for it. Having flexible configuration files sounds like a terrible idea. I don't want my mistakes to fail silently. Not to mention that the only problem the author mentions is trailing commas... as mentioned better by others, lack of programmability is a feature, not a bug. Configuration files are presets and markers, not functionality.