What do you Mean, There's Already a Protocol for Accessing Resources?
Of course, once you move to having every WS-RF resource defined by a unique URL, there is a well known operation for reading or writing state, operations that need neither WS-RF or WS-Transfer. Also, these well-known operations have working support for multimedia and other non-XML contents, an efficient way of probing for changes since the last fetch, and built in support by 100% of all application servers.
Yes, HTTP HEAD, GET, POST, PUT and DELETE can all be used to model stateful resources.