"...and DRM is explicitly allowed to be broken on out of copyright works.",
This brings to mind a point I made when DRM first started doing the rounds and again when laws were brought in making it illegal to "hack" or reverse-engineer the encryption. What happens to a copyrighted work when the copyright expires but the only copies available are DRMed? Does the law allow for "cracking" DRM on a work with an expired copyright or was that scenario never envisaged by the lawmakers?
No doubt the copyright holder will have a non-DRMed version of the work, but they are under no obligation to release that once the copyright expires. They can just keep selling the DRMed version.