Rare and out of print does not mean important or valuable.
It doesn't automatically mean pointless or worthless, either. And it's too late to judge either way once it's been destroyed.
Usually it means the opposite. Books that are old and valuable tend to be out of copyright, so they do see new printing runs.
It doesn't automatically mean pointless or worthless, either. And it's too late to judge either way once it's been destroyed.