After a night's reflection, I'd like to add a story.
When I was first learning bolero, it was summertime, when I like to wear big, breezy skirts, which I wore to my lessons. After a month of working on bolero, one day I went to my lesson in pants and found out that I'd been doing the basic wrong all along, because my instructor couldn't see my legs!
Since then, I've attempted to wear something a little form-fitting, especially for rhythm/Latin dances. There's so much going on with leg action and body action, and it's important to be able to see your body's movement.