Any book is the child of its own times, rather obviously. This means that sometimes parts of even great books do not necessarily age well. Examples the author uses to make his case may appear rather obvious to the contemporary reader, but alien to posterity.
Some examples are immortal, such as Leonard Read's magnificent little story, "I, Pencil", which resembles Walter Lippmann's breakfast and Adam Smith's woolen coat. But, giving lectures to high school students in Italy and using "I, Pencil" regularly, I can tell you that sometimes I have the impression that youngsters today find the very idea of talking about pencils so...exotic. Well, they have still seen pencils, and some of them still use them, so in a way that adds up to the power of Read's story: see the marvels of cooperation in objects of sheer simplicity.
But what about Adam Smith's pin factory? What are pins really for? I can picture a young kid asking this question, particularly as she may have never seen her grand-mother working at her sewing machine or mending clothes (a far more common picture just a few years ago; my grand-mother always had a sewing machine in her apartment).
Virginia Postrel has a great article on Reason on what pins were, at the time Adam Smith picked the pin factory example to explain a more and more complex division of labour. She explains:
Nowadays, we think of straight pins as sewing supplies. But they weren't always a specialty product. In Smith's time and for a century after, pins were a multipurpose fastening technology. Straight pins functioned as buttons, snaps, hooks and eyes, safety pins, zippers, and Velcro. They closed ladies' bodices, secured men's neckerchiefs, and held on babies' diapers. A prudent 19th century woman always kept a supply at hand, leading a Chicago Tribune writer to opine that the practice encouraged poor workmanship in women's clothes: "The greatest scorner of woman is the maker of the readymade, who would not dare to sew on masculine buttons with but a single thread, yet will be content to give the feminine hook and eye but a promise of fixedness, trusting to the pin to do the rest."