If you could get certificates for them, so could anyone else including your adversaries, since there is no system of ownership for them. It would be like issuing certs for https://192.168.1.1
They're likely be part of a cafe/hotel/guest wlan or a poorly managed "intranet" full of vulnerable stuff that needs to be shielded from CSRF. That's in addition to having ambiguous addresses. So should definitely be treated as less safe.
