Have you noticed that book covers have changed?
The predominance of cover 'art' is being replaced by a new design goal; big and bold.
Is this to make books stand out on book shelves more?
Cover art, complex designs, small or script titling, even subtle photographs are perfect for when the reader picks up the book before choosing to buy it; at an airport book shop, typically.
But these kinds of covers are next to useless, illegible, in the place that most people will see the book - on a web page.
Huge, clear, colourful text with a title that fills the entire front of the book, simple geometric designs and high contrast covers are the order of the day.
In the 'flesh', they might look garish but as a thumbnail image on a web page, they are competing with the site's own branding and adverts.
The Internet has led to many changes in design philosophy in all kinds of areas; writing, graphic design, user functionality, and so book cover design is simply one more area that the Internet is now influencing.
So remember, don't judge a book by its cover.