In your world, perhaps. I see people process through the checkpoint everyday and they either automatically take their shoes off or ask if they need to remove them. The point being, which you conveniently glossed over, is that many people still wear their shoes barefoot or don't think to pack an extra pair of socks specifically for the purpose of passing through security. I don't understand the concern over cleanliness of the floors or the bins when people don't take enough precautions on their own to keep their feet clean. In fact, Americans in general don't keep their feet clean.

As for the soundness of removing shoes, I agree. There has got to be a better way. The current policy ain't it. However, I'm afraid that the bureaucratic path of least resistance is to stick to the current policy of having all shoes removed than to return to the previous policy of letting officers use their judgment on which shoes ought to be removed and which shouldn't.