God’s permissibility is not synonymous with God’s injunction.
Every such thing, just because allowed or not explicitly prohibited by God, does not make it obligatory on Muslims to follow at all costs. Normally, they can follow that permissibility within the bounds as allowed by God, but whenever there is Human Rights infringement, state is bound to act and provide justice to aggrieved party. Usually it happens even today on a case by case basis for many laws, but when such infringement becomes so pervasive in a society, then justice demands that state should intervene at a broader level through law-making initiative.
Every such intervention by state will be temporary and could be revised at any time. Besides, this right was given to a Husband and Husband is giving-up that right in favour of state. Nushuz will not be forgiven, instead, it will be dealt with by the state to prevent its unfair use at the hands of husband which at times can become very pervasive in a society. The illat of this permissibility will still be met.