It’s conservation. Archeology is digging up what was once lost.
So finding a lost video game is archeology. Keeping it safe is conservation.
Ensuring games can’t be lost in the first place and that they continue to work in the future is preservation.
All needed, but different things.
I think lifetime of original creator is fine. I wrote my first manga in 2010 (it’s crap but still), I don’t think that it should stop being mine in 4 years.
I heard that lifetime + 80 was to stop someone murdering a popular author and, assuming they got away with it, then publishing that work for their own profit. But I don’t know if that’s true.
That is solved with different degrees of copyright. If done right, the author’s works will never stop being theirs, but people will be able to make fanfiction without fear of a bloodthirsty copyright lawyer biting at their necks. They’d just have to clearly indicate it’s fanfic, and the original author could get a cut of any earnings past a threshold.
Create a great work that inspires another great work; both authors benefit.