As a customer, I don't have much use for ratings without reviews, particularly for creative products. As I mentioned above, people's standards are so different that a star rating without knowing anything about the rater's taste or criteria is meaningless.
From that standpoint, adding a second set of ratings to the product page, unless the Goodreads reviews themselves also transfer over, is just more clutter on a page that already has more than enough. And to the extent that some of them might be wildly inconsistent, given the different ways each rating is described, makes the addition of Goodreads even less helpful.
A short time ago, Doordash, the restaurant delivery service, starting adding Google restaurant ratings to its own rating system, so that both scores were displayed for each restaurant. That didn't last very long, I suspect because it didn't make a positive difference for customers.
That said, Amazon also owns IMDB, and it already draws on that for movie and TV ratings. Of course, IMDB has a ten-point scale, and Amazon offers no guidance about how to interpret it. On IMDB, it offers only guidance for what a one is (terrible) and what a ten is (excellent), leaving what the other ratings are up in the air, except that they obviously fall between the two extremes. So yes, I suppose they will inevitably make the same use of Goodreads as they do of IMDB.
