Some people just can´t see the value of book covers. In a way, the argument that covers are not a truthful exposition of the book´s content may hold true. So if a person judges a book by its cover, he or she has a sort of implicit prejudice imbued in themselves, a pre definined concept of what the book may hold before even opening it. Well, I´m sorry to break it to you, but those people don´t have the slightest idea of what they are talking about.
Book covers are important. Period.
Let´s start by attraction. If a person it´s pretty, has a delightful body and lovely face, he or she are already one step ahead in your scale of the perfect person. Now, you might say I´m shallow, but I have never heard someone that, all variables maintained equal, prefers to date an ugly person than a pretty one. And I do know that beauty is in the eye of the beholder, but so is a book´s beauty. It works the same way at all levels. The content and the inside of the book is obviously more important than its cover. But don´t you rather have a pretty book than an ugly one?
Another point, decoration. People decorate their houses and offices with all sorts of objects: vases, ashtrays, porcelain, silver boxes, flowers, and guess what, books with pretty covers…None of these objects, except the books, have any inside content. It´s not like you open up a flower and you find a treasure of knowledge or just a cool little tale to explore. Therefore, if we eliminate the fact that books have awesome things inside them, they can still serve the sole purpose of decoration. So yes, books with nice covers are better because they can fulfill different purposes.
One last argument, book covers do give a glimpse of what´s written inside them to the potential reader. This is not true for all books, but we may say that, usually, a good book has a good cover. Therefore, it´s actually is a smart move to choose a book by its cover when wandering about in a bookstore. Of course, there are excellent books with horrible covers and vice-versa, but chances are in your favor that a good cover holds inside good content, when picking randomly. My point here is: decisions based on first impressions do count, because, more times than fewer, they are correct. If it looks like a duck, swims like a duck, and quacks like a duck, then it probably is a duck.
Besides, I rather own amazing and beautiful looking books than ugly ones.
Just my two cents.