Google is not obligated to provide a Content ID system; they're only obligated to make it possible for someone else to do so. So if Google wants to tie their Content ID system to their monetization system and put other restrictions on it, that's 100% ok. If you don't like their terms, you're still free to use other means to police for infringement of your content.

As for them no longer being able to identify other instances of your work after you sever the relationship with Google: once you do so, they've got no license from you that authorizes them to keep authoritative copies of your works around.