I think this is an entirely valid criticism of yaml. I'd absolutely support there being a simplified form of yaml (YAML The Good Parts?) that covers what people actually want to do and doesn't try to be a swiss army knife object serialization format.
Problem is people don't agree on Good Parts. People seem to think keeping YAML a superset of JSON is the good part. I'd think otherwise.
Anyway, http://ogdl.org/ is one candidate for YTGP (YAML The good parts) but it's comments can carry metadata, which is a huge turn-off, others think TOML (https://github.com/mojombo/toml) is a good replacement, but it has no support for alternate number types. You write in something like
Ideally you would have a strict subset of YAML rather than a totally different language for compatibility reasons. You can call it the Friendly, Readable, Declarative YAML standard so we can have a standards war that is FRDY vs. JSON.
