11. Women and girls should, whenever possible, wear dresses.

The rationale is royal procedure.
Not at all.
As a symbol of prestige, young boys in the Royal Family are expected to wear shorts. In a similar vein, young ladies from the Royal Family are supposed to wear smock dresses when they go out with their parents.
When feasible, girls and women should wear dresses. © Getty Images/Antony Jones
The royal family has maintained this custom since Princess Anne, the daughter of Queen Elizabeth, started it. Princess Charlotte is required to wear dresses, which is why you see her wearing them so frequently.