Short answer: The rents. The rents are high and the margins are too small. So say the current and former Ann Arbor booksellers who were interviewed by Domenica Trevor for her Ann Arbor Chronicle piece about the economics of the bookstore business in Ann Arbor. Interesting conundrum. But I am sure that somehow or another the market will sort that issue out. It's the larger cultural change that worries me.
The sad reality is that books are becoming an expensive hobby like fine wines, exotic foods, horse racing, classic cars or Cuban cigars. For the class of people with lots of disposable income and intellectual refinement and who also have an interest in browsing around looking for books to read. Like the kind of people who browse estate sales and antique shops looking for just the right armoire for their guest bedroom instead of buying one from an Ikea warehouse outlet. The rest of us can just buy what we want off Amazon for our Kindles or at the ground floor display at Barnes & Noble if we don't have a Kindle. Because for most of us time is money and money is dear. That's reality and it is indeed sad.