Those laws exist to protect the rights of the creator for a period of time; if they want a thing to pass into history, without openly publishing the source, that's their prerogative.
Even before copyright expiration, anyone can clean-room reimplement a thing in open source if they wanted to, and not be violating copyright. This has been common in OSS. (Samba for example)
The period is effectively infinite now, since congress keeps retroactively extending it.
Also, the SMB protocol does not contain any copyrightable material, like music, sprites, icons, game assets, etc. Copyright law prevents you from faithfully cloning (pixel for pixel) most GUIs and games (so most phone apps)
The Sonny Bono act was passed 19 years ago. 100 years of protection isn't infinite. It also requires an entity to WANT to enforce that copyright. if they exist, then you really don't have a right to pixel clone something - they can keep it buried.
There are plenty of game variants created that capture the feel of prior games without being IP violations
Even before copyright expiration, anyone can clean-room reimplement a thing in open source if they wanted to, and not be violating copyright. This has been common in OSS. (Samba for example)