I came of age and went to college in the late 1970s. I can remember when women wore leotards as outerwear everyplace they went. Long-sleeved ones, the most elegant kind. The last time I can remember seeing leotards worn outside was circa 1982.
The trend seems to have started among women college students in the Northeast during the 1940s and 50s. That was when Martha Graham established the leotard as standard dancewear. (I read this once in a history of modern dance.) The college women as well as Greenwich Village bohemians found them so stylish as well as comfortable that they took them from the dance studio to the streets. That lasted through the 60s and 70s until the early 80s, when long-sleeved leotards mysteriously vanished from everywhere except ballet school.
Women looked so excellent in them, why did they have to quit? Will they ever return?