Back in the nineteenth century European visitors to the US were astonished, repelled and disgusted by some American habits. Yankee males were addicted to chewing tobacco, which they enthusiastically spit on the floor or wherever. They clumped around the house in heavy boots, sometimes with hobnails or caulks. They were pigs.
Not anymore. America has joined the Arab world and the Land of the Rising Sun in unofficially banning footwear in houses. Why should this be? It has no doubt come to the attention of many that it is a custom among some cultures not to wear shoes indoors. Americans foolish enough to install light-colored wall-to-wall carpeting are leaders in the drive to make visitors pad about in their stocking feet. The women, and perhaps men as well, who maintain domestic floors seem to feel that forbidding shoes will keep floors cleaner and thus lessen the frequency and intensity of sweeping, mopping and vacuuming. Of course, that's the kind of logic that keeps paper plate and plastic utensil sales growing. The phenomenon has been encouraged as well by new footwear designs, like the silly plastic "Crocs" which are easily removed when entering the neighbor's foyer.
Does anyone seriously believe that an unshod foot is particularly clean? You might be OK with shaking the neighbor's hand but you're probably not too enthusiastic about shaking his foot. Is there some sort of psychological phobia about the world's outdoor surface detritus that requires it to be kept outside the threshold?
The best way Westerners could show unity against fanatical Islam would be to once again allow shoes indoors.
At my house, there's no compulsion to remove your shoes. Sadly, however, those that don't are usually forced to burn their shoes before they can re-enter their own home.