My husband is a big fan of the leggings, lol. I sort of agree, at least in the sense of agreeing there are 'going out clothes' and 'work clothes ' and so on. But times change, and I'm really very glad for the expansion of what is acceptable and the demise of enforced clothing styles as part of enforced gender roles and class roles and so on.
I don't know if OP is old enough to remember when fashion was so rigid that I could wear blue nail polish and get literal gasps of shock from old ladies; IMO what we have now is better.
Just dress to your own standards and leave everyone else to dress how they want. Declasse is a fantastic word though.