What is the wisdom behind not exempting some cases from the legal inheritance between brothers and sisters, even though the female may be more in need of money than the male?

Allah Almighty in the inheritance enjoins that the male shall have the share of two females, as stated in His saying: "Allah instructs you concerning your children: for the male, what is equal to the share of two females." Allah did not differentiate between rich and poor, and upon the servants is to listen and obey.