Digital publishing has put authors and readers on the horns of some painful dilemnas.
We have about 500 years of experience handling physical printed books. We've evolved a network of rules and laws governing pricing, sale, author royalties, righs ownership and copyright. Now we are trying to retrofit these concepts into digital publishing. This is going about as smoothly as jamming a square peg into a round hole, and case law is not exactly clear on how to chip away at the rough edges.
Physical books cease generating any revenue for the publisher or the author after the first sale. After that, the book can be lent out, resold as used, copied partially for fair academic use or given away and none of these activities generate any additional revenue for anyone.
Digital rights can change the nature of the book from something we hold, own and read into a body of digital text that is "leased" to the reader. Every time someone else wants to look at the book, the right to look at it can be sold again. The price can be changed to suit the circumstances.
The Google decision robs publishers and authors of that additional revenue opportunity. But it will be good for readers, as any book you look for will be in "digital print", even if it has ceased to exist in the used book marketplace.