I get to go old school with this reference. Basically male and female circulation systems act differently in cold weather. Men tend to keep blood flowing to all their extremities in cold weather, women tend to keep your core temperature consistent and reduce the flow of blood to extremities.
So men don't feel as cold, but they're burning more energy, and their core temperature can dip more. Women feel colder, but they're core temperature is more stable, and doesn't dip as much.
In real life we experienced this as women are often colder in the same environment men are comfortable in. Because of physiological differences in blood flow during cold weather events.
So legs stockings are both an effort to keep the body warmer, be fashionable, and maybe do some body shaping. But you're more likely to see them in the winter, in colder climates.
Anecdotal data: in Southeast Asia I never see leggings, even in " winter ". In Japan I see leggings all the time.
This makes sense. But it doesn't explain why I have to wear a jacket and pants to work everyday while the colder-extremities-sex wears sleeveless dresses.
I feel it would work better for everyone if we all switched to long, flowing, wizard robes (short or long sleeve optional) in all professional fields.
Bring up your dress code with your employer. Tell them you are concerned it is not inclusive enough. My boss very quickly added that the pictures are just guidelines and if it falls within the office appropriate "business casual" guidelines then it's fine. Our dress code genderless and allows for cultural clothing even though it didn't specify that.
I agree with the robes though. Summer climates especially require a more Middle Eastern type clothing. Light layers, light colours, and lots of airflow.