Why is the world so full of meanness?

I often wonder wy the wold is full of meanness, restrictions, and can'ts. Why can't a boy wear a pretty dress? Why can't everyone want to feel pretty if they want to?Why is it wrong if I love heels? Why can't a boy dream of being a bride? Why does society perpetuate restrictions on people on who they want to be or how they want to appear? I don't get it.