The dilemma is similar in the iBookstore, but over there iBooks Author is at least partly to blame. What appears to be a book cover (called a "title page" in iBA) actually appears full-size on an iPad only for a few seconds when a book is opened. The title page mostly appears as a thumbnail either in the store or in a reader's library. However, it's not actually a different image; the same image is scaled down to thumbnail-size. And yet there's no indication that the title page will ever appear thumbnail-size during the design process. You have to preview the book on an iPad to see it that way.
The dilemma is similar in the iBookstore, but over there iBooks Author is at least partly to blame. What appears to be a book cover (called a "title page" in iBA) actually appears full-size on an iPad only for a few seconds when a book is opened. The title page mostly appears as a thumbnail either in the store or in a reader's library. However, it's not actually a different image; the same image is scaled down to thumbnail-size. And yet there's no indication that the title page will ever appear thumbnail-size during the design process. You have to preview the book on an iPad to see it that way.