New twist to judging a book by its cover?

This tangent was prompted by a GoodReads review of Laurel Snyder’s excellent novel Bigger than a Bread Box.

Unlike Trudi, I was not drawn to Bigger than a Bread Box because of the cover art. For months, the only cover art I saw was about the same size you see above — thumbnails on GoodReads and Facebook and Twitter. I didn’t find it dazzling. I actually thought Rebecca looked mighty scary. I didn’t understand why Laurel was all pleased with the cover art until I got a full-sized copy in my hands. Then, I was sold.

Speaking of bread books, I also didn’t get the cover of Breadcrumbs at first (I shrank the image to the left so it was about the size of the icons I see). Similar situation. I saw all the buzz about it on GoodReads and blogs, but I didn’t even realize there was a GIRL and a bunch of WOLVES on the cover until my copy arrived at the library (I’m blind). MUCH more interesting at full size, and very lovely. I thought the book was going to be much “prettier” until I saw the cover in person. It reminded me of Kira Kira, which bored me out of my skull.

Is scaling something book cover designers consider when they lay out a novel? Is a book’s appeal in a smaller size more important now, with thumbnails accompanying many social media references? Or is it comprable to the way it was in the past, when thumbnails appeared in publisher catalogs?

I suppose it’s always a matter of taste, right? I mean, for example, the designer of Countdown made a deliberate choice to have a bolder, straightforward design. Do designers pay attention to the tone of the book? If so, how do gross oversights like those in The Romeo and Juliet Code and The Trouble with May Amelia happen? Does it just come down to designer and publisher preference? I know Laurel once told me authors don’t have much say in cover design. Am I overthinking this?