Trillium,
Let's be clear about a few things. The only data that checkusers get is a subset of the data that the WMF webservers (and all other webservers throughout the Internet) collect on all visitors. This is data that is voluntarily disclosed by readers (although they may not all be aware of it). The checkusers get substantially less information than is actually available, and only on those users who *edit* and not those who simply view. That means that while you are correct, the Wikimedia community at large certainly includes all readers, only editors are stakeholders in the exposure of certain data to checkusers.
There is no legal requirement in the U.S. to make this information invisible (AFAIK). The only limitations are those imposed by the Terms of Service. The previous privacy policy referred to the identification of volunteers to whom certain limited information is exposed, but when Michelle and others said that the policy itself wasn't being effectively enforced more was at issue than how (or if) the IDs were stored. The WMF has never had a method of verifying received identification. Because of the international nature of the movement, IDs were submitted in languages no one at the WMF speaks, from countries and authorities around the world. As a result, anyone could easily submit a false, altered or misleading identification. The identities provided by users with advanced permissions could never be relied upon.
So if you want to argue that such users should be positively identified, then please make some practical suggestions (which you have conspicuously avoided doing so far). How should identities be confirmed? In what circumstances should the ID information be disclosed, and to whom? What, fundamentally, is the usefulness in collecting this information to begin with? What are the use cases in which it is necessary?
Thanks in advance for providing us with such useful advice!