These books are out of print, but still under copyright.
I can see some advantages: world wide access to a massive database of literature; the system will help authors to reclaim their work if they please; and so forth.
But why on earth should google be allowed to control these works, charge whatever price they please, when all they have done is scanned the text into a database?
If they allow them to be viewed freely on the Google Books service, this is a good thing. But I would agree that should Google start to publish them and claim the rights to profits from them, this would not be a good thing.