The most obvious reason is ,IT is about being human, Basic biology!
[How come when you walk into a hardware store and ask for a male or female part ,they will give it to you ?!?]
You also should read the written dissents of Justices Roberts ,Scalia ,Thomas and Alito
In Brief:
“A nation, as a society, forms a moral person, and every member of it is personally responsible for his society.”
“We have now sunk to a depth at which restatement of the obvious is the first duty of intelligent men.”