When did it become normal for girls to wear really tight sweats/yoga pants/athletic running tights as everyday items of clothing. Not saying I mind, but I don’t remember anything so revealing being worn when I was in school a mere ten years ago (I am fairly certain I would remember).
Honestly I don’t think about it being revealing or fashionable. I just feel uncomfortable wearing baggy clothes because I can’t see my own body or ‘feel’ it if that makes sense. Plus I almost always fall over by tripping on the baggy hem of sweatpants- So I avoid it all together. :]
I don’t know when it became fashionable to wear yoga pants outside the gym/studio, but I know they are the most comfortable pants out there, so they play double duty as pajama pants for me. 
Being a male student I don’t find the need to wear the tight pants 
A pair of loose athletic shorts works just fine for me, and there are a number of ladies in my classes who choose the same.