An under-appreciated consequence of extremely long copyrights

This is one of the unforeseen consequences of extremely long copyright terms:

Not only have many copyright holders failed to keep their older works in print, but there are now many books whose copyright holders can't be identified at all. In many cases, the original copyright holder is dead and records about who now holds the copyright aren't available. These "orphan works" have become a serious problem for projects such as Google Books, which aims to digitize books and make them available to the public. Google can't obtain the rights to reproduce these books at any price because it can't figure out who it needs to negotiate with. The older a work is, the more likely it is to be orphaned, so copyright extensions have made the problem much worse.

At some point the interests of the creator of the work are more likely served by allowing their creation to be published and enjoyed rather than left to wither on the vine.  If nobody can even figure out who owns these rights then precisely who is being protected?