I have to confess that I didn't read Mazzone's paper, just the summary. The article sounded interesting enough to point to if only to engender some debate, because I agree very strongly that copyright interests have pushed the needle too far in the direction of limiting the rights of the public.
Sounds like you have some very relevant experience, though, and that the issue is more complex than it sounds on the surface. And I certainly agree that we don't need more government intervention.
That being said, the very lack of clarity about copyright that you mention means that the assertion of rights in association with a public domain or out of copyright work ought to be more specific than saying "All Rights Reserved" and leaving it unclear just what rights are owned.
For example, when we published modified editions of the freely redistributable X Window System documentation in 1988, we made very clear in the copyright notice that it was our modifications that were copyrighted, and not the entire work.
I remember again Lao Tzu's immortal words: "Losing the way of life, men rely on goodness. Losing goodness, they rely on laws." We get calls for more laws because of the many abuses that have been carried out in the name of extending intellectual property. There are many cases where seemingly incidental improvements to a public domain text have been leveraged into a near-monopoly position because people didn't realize early enough what they were getting into. (I'm thinking particularly of West's legal citation system, which has done copyright jujitsu to create effective ownership of a body of otherwise public domain content. No one questions the value of West's citation system, but the unintended consequence was to grant an unintended monopoly on referencing otherwise public domain texts.)