You can already describe URI parameters in structured way with the new API Blueprint format. Refer to https://github.com/apiaryio/api-blueprint/blob/master/examples/7.%20Parameters.md for details.
The new format is now default and URI parameters are properly rendered in the documentation.
We are still working on description of http message–body properties (parameters). It is planned in the upcoming revision 1B of API Blueprint – as discussed in https://github.com/apiaryio/api-blueprint/issues/25
Thanks for your feedback Jeremy. We suggest documenting only main/functional aspects of the API. It is assumed that not-mentioned URLs+verb combinations return some sort of error code. You could specify common behavior of the API (for example error handling for unsupported verbs/URLs) in the header comments of your API.
Does that make sense? My worry is that featuring all verbs for all URLs will clutter the documentation, too.