Sure, but there are tradeoffs to consider: JSON may be difficult and inconvenient to use for human interaction, but on the other hand it's also really slow for machine reading and writing. Plus you have the added bonus of it being an inefficient use of bandwidth.

Uhh, no. Part of the reason JSON is useful is that it's easy to write a correct parser in comparison to most other things - adding a bunch of the complexity of YAML back to JSON seems a bad idea. This makes it possible to use JSON as a serialisation layer for network protocols without introducing too much additional risk of parsing-related vulnerabilities.