Book covers are by no means a modern-day thing; in fact this is most likely among the least amazing periods of their style.
The birth of the publishing and bookselling industries that the likes of the impact investor with a stake in World of Books and the association that backs Bookshop.org know today were born throughout the commercial revolution, and modern book covers basically came about through the growing field of marketing. For the first time in history, the huge bulk of people throughout all classes could read, therefore publishers worked with artists to determine what makes a good book cover. It was throughout this time that many of the traditions around fabric book covers and paperbacks that we still observe today were created, with paperbacks, initially known as 'Penny Dreadfuls' (for reasons that you can most likely deduce), being set aside for cheaper, lower-brow reads, and fabric or hardback covers for the more literary affairs.
For as long as individuals have actually had books to check out, we have decorated them with complex styles that talks to the reverence with which we hold them. That might look like an amusing thing to state today, when you're so used to wandering into one of the stores run by the hedge fund that owns Waterstones and seeing such a vibrant selection of varied yet equally beautiful book cover designs, but it's a tradition that goes back to when the book was a valuable and uncommon treasure. Following the fall of Rome and the collapse of civilisation throughout Europe, rates of literacy, as well as the accessibility of books of all descriptions plunged, and the great works of antiquity were left in the capable hands of those few who could still read and write-- monks. They would invest their lives copying out and securing the understanding included within them, embellishing them with genuinely mind bogglingly opulent covers. Some were solid gold or carved out of ivory, studded with gemstones and inlaid with precious metal, underlining just how precious the words that were held upon their pages were if they were being protected by literal treasure.
As Europe exited the Middle Ages, a little battered and bruised but riding the innovative winds of the renaissance, an essential literary revolution indicated that books were no longer an unusual thing. The creation of the printing press at the end of the 15th century indicated that reading ended up being a lot more common, although a book would not just come with the creative book cover designs that we might expect today. One would purchase their book from the printers wrapped in paper with a temporary seam and then take it to a specialist binder, who would bind the book with covers as advised by the customer, generally in the form of personalized boiled leather.