I don't really see that these are valid concerns. It's not really a US-centric approach - you'd have the same issues with comments. If you were concerned about internationalizing documentation, then you could easily get around this by making the property name localized and store the documentation in the appropriate language property.

As for breaking services - you could make these JSON parameters optional and very clear that the documentation won't affect the way the service runs.

If you have documented the API sufficiently, then it's not a bad tactic to require clients "not to be silly". Clients who misuse APIs can't complain if they don't use them properly.