I agree that this is indeed on point.
Personally I would like $request->getQueryParameter() and $request->getBody() over $request->get() and $request->post().
In the former case you are asking for the parameters in the query string (query component of the URI) and the latter is to get the request body. These method names make it very clear what you're asking for.
What kind of bothers me in general about this RFC is that... we are talking about Request and Response and these are standard HTTP components, yet the RFC is about providing wrappers for existing global PHP variables and functions. It does not try to model these components as they are in their standard, nor aim to do so.
This is why I believe it's better to leave it to userland implementations. Besides the fact that they are widely adopted, they attempt to follow the specification they are providing.
Ekin H. Bayar