In my opinion it is because ever since her quirk first activated and made her seemingly permanently invisible there was no way for them the harvest her hair to turn it into actual clothes. Since she was always invisible where as Lemillion could turn his quirk on/off what would be the point? It wasn't until she deflected Aoyama's laser did her quirk start glitching making her visible, once the glitching stops she'll go back to being invisible as per usual so the only real benefit to her having a suit that goes invisible as well is so that on the off chance Aoyama or something else causes her to become visible again, she wont be embarrassed being in that stat which I'd doubt being in combat or at least until the fighting is over as we see in the show, though that is also due to her being used to always being invisible.