I'm not in the biz and so don't by any means have the ability to dispute you, but I'd say it is much easier now with the existence of memories alpha and beta to keep everything in agreement as well as with there not being any prime universe screen material for the foreseeable future. I see little reason why the books falling under the "relaunch" category couldn't be canonized. I also think if the franchise were to say "the franchise books are to be considered canon and if a future tv show is produced we will try to prevent it from contradicting them" readership would go up.
When I have polled members at st.com, most there consider the books nothing more than fan fiction they have to pay for and don't appreciate the editorial controls and licensing that goes into them. I get ignored when I site the books in discussions there with "the books are meaningless" or "the books don't count".