Is any party member actually in standard dress? No one but Yukari has that pink uniform. Junpei's hat? Akihiko's bright red vest? Aigis' headband? Main dude, just like Yosuke, somehow gets away with wearing headphones during class at all times.
At least Mitsuru can argue that she doesn't know how plebs are supposed to dress.
*You need to be a genius just to date her*
*She doesn't know how to eat ramen.*
They actually wear the correct uniform, except Fuuka. Yukari just has a cardigan over her uniform, Mitsuru has forgone the jacket, as has Akihiko, and apparently the teachers don't care if you wear headphones in class so as long as you're not bothering anyone.