ON Nov. 1, just two months shy of its 50th birthday, the plastic pink flamingo went extinct. Or more accurately, it stopped reproducing, when its manufacturer, Union Products, shut down the factory in Leominster, Mass. That’s sad news, but hardly surprising. The flamingo’s glory days were behind it. Union Products cited the rising cost of plastic resins and of electricity, along with financing woes. Yet while the bird reigned as an icon in the late 20th century, it was bound to succumb to the very different tastes — or the absence thereof — in the 21st. In 1957, the flamingo...