Are all leggings that are made intended to be worn under clothes or covered by them if manufactured with pockets?

disclaimer This is not a question of if leggings should or should not be worn and by whom. It is not a question

If all leggings were made to be worn under a skirt or long drape top, why would so many made these days, at least in this area if you have not seen them in yours, made with pockets? Even if the pockets are merely decorative and ornamental, or marginally useful why would a manufacture put them on there and put them on in a way that had visual aesthetic to the garment? If the pocket was to be merely useful, why not construct it so that it would be internal and not seen?