It's quite true that the bookstore owners should not have to subsidize the browsing and selection process of people who have no intention of actually buying those books from the stores. It reminds me of an observation made by Henry Hazlitt, in his classic "Economics in One Lesson": A key to correct economic analysis is thinking through the long-term and unintended consequences of all actions in the marketplace.
Another way in which the brick-and-mortar booksellers are hurt, is the damage done to technical books when they are used repeatedly as reference books by techies seeking answers to questions, or students spreading them out on the floors and doing their homework. Even worse is the practice of slitting open the plastic sleeves in the back, extracting the CD-ROMs, and burning a copy using their laptop computers. A similar practice is actually stealing the CD (which alone does not have any sort of theft-deterrence magnetic tag). Just the other day I opened up a large technical book at Bookstar, flipped open the back cover to see if the book had an accompanying CD, and found the sleeve to be empty.
Let's hope that owners of bookstores do not have to resort to closing their doors to get the message across to folks who are taking them for granted.