Hadith On Hazrat Fatimah Covering From Head To Toe
The Quran allows showing hidden zeenat to slaves, though he is not mehram. Not only does it allow slaves, but also allows showing zeenat to the men who are dependent on the family and feel no inclination towards the women of the family they depend upon. It means that showing hidden Zeenat is not only allowed for mehram but also for some other individuals, who are not mehram, mentioned in the verse.
We need to understand the injunction. If a woman is not wearing a zeenat, she just needs to cover her private parts. The whole body is not required to be covered. However, if a woman prefers to cover herself completely, it is her choice.