>>712938862In my unprofessional opinion: they direct gaze.
Thighhighs cover most of the legs, any imperceptions or oddities are hidden and raise the view upwards.
Mayl's skirt is short, really short. It's so tantalisingly short that it becomes almost impractical if you consider her doing anything except standing.
When you put both of these together you have all your attention on this small slither of skin between the top of the thighhigh and the base of the skirt.
Every movement shows a little bit more but never quite enough. It's a near constant tease.