What is the answer to the objection raised regarding the reason for the obligation of the hijab, and does the ruling change if the hijab becomes a cause of harm, and why have jurists overlooked the reason explicitly stated in the verse: "That is more suitable that they should be known and not be abused"?

The wisdom behind the فرض (imposition) of hijab is that women are recognized for their chastity and thus not harmed. If societal standards change such that harm befalls the chaste woman, then it is a corrupt society whose norms are not to be heeded. The illah (underlying reason/effective cause) for the imposition of hijab is that a woman is a mature female. There is a difference between the illah of a ruling and its hikmah (wisdom). Rulings revolve around their illat (causes), not their hikmah (wisdoms). No reputable jurist has ever stated that the illah for the imposition of hijab is to prevent fitnah (temptation/strife). Rather, preventing fitnah is mentioned in relation to the ruling on looking at what is not awrah (nakedness/private parts). The Quran exempted from hijab those men who lack sexual desire (ghayr uli al-irbah min al-rijal), children, and elderly women due to the absence of fitnah.