Users would like to have anonymous read (pull) access to docker repositories in Nexus. This helps consume and share docker images more easily by not requiring a specific login. This is analogous to the benefits offered by anonymous access by other formats.
As an end user, I don't want to have to configure authentication for read only access to docker repositories. Docker hub does not require this, and neither should Nexus Repository Manager.
According to this comment from a Docker developer the correct way to do this would be to implement token authentication, and to have Nexus hand out tokens for anonymous access:
There might also be a simpler implementation that should be considered for blanket anonymous access to a repository.