I'm wondering how this dedication on the front cover works. For instance, will it be in a complementary font/color to the title and author's name? If it isn't, will the authors have any recourse, given that PA is unlikely to run it by them for approval before printing the books?
And if the cover is filled with text/images - wouldn't that get a bit cluttery? Then again, I suppose the rationale is that Oprah will be so delighted to see a book with her name on the cover that she won't care about the aesthetics of it.
Either way, though, these are books that most likely cannot and will not be sold, meaning that the authors will never recoup their investment. Also, they won't get royalties.
Once we print their name on your book's front cover, together with yours, you have their attention. They will show it to others, guaranteed.
So the implication to me is that the book alone didn't catch the attention of family members and friends. They didn't bother showing it to others. However, printing their name on the cover changes everything!