> The CO has taken the (entirely correct) position that copyright law exists to incentivize human acts of creative expression.

The US Constitution grants Congress the power to grant copyrights "to promote the progress of Science and the useful Arts." Creative expression that is not useful therefore is not constitutionally copyrightable.

But that aside, I agree with the author that the Copyright Office refusing to further expand the already vastly over-expanded scope of copyrights is a rare positive ruling.