We would want this false in openstack and rhev.

In openstack some hypervisors may be esx, others can be rhel (already registered).  We do not want to accidentally create another consumer to represent one we already have on a rhel box, but there does need to be some configuration to add the hypervisorId to that consumer based on a broader lookup.

In rhev we currently use virt-who behavior that mirrors esx, but all the systems are theoretically registered, so we should provide a way to update all the guest data from a cluster type virt-who without accidentally creating parallel consumers.
 * In this case, we're probably better off getting each system to report its own guests, but I'd feel better keeping the create_missing flag just in case