We'll just have to disagree there.
In any case, if you find REST restrictive, fine, go ahead and do your RPC. Just don't try to tell me that it's anything other than RPC, with all the problems and warts we all know.
The value in REST is exactly that it forces you to simplify your interface down to basic verbs that everyone can understand and work with; if you can't do that, if additional complexity is unavoidable, then REST is not for you and you should be aware that your application is now officially complex, maybe too complex to be a public API.
From that point of view, something like SOAP is a perfectly respectable protocol and you should use that instead.