The term is not so much of a “wasted blessing” as it better translated and understood as a “ blessing for nought” or a nullified blessing. In Hebrew it is a “bracha l’vatala,” from the word nullification-like we nullify our leaven before Passover.
I have read that there is controversy about whether the Wailing Wall truly is a remnant of the Second Temple or whether it is part of a Roman fortress. What does the evidence indicate?