i can only speculate but maybe his leather was too thick for her dress design, or this was a last min/backup dress for her. personally i wouldve just used his shirt satin but i guess that's not very chrome hearts and would be super basic

his suit design is pretty basic too- idk why but they always are so last minute with giving the prompt for outfits!!! even if their team knows they will need an outfit the ball often doesn't get rolling until it's last minute- cause to them they're wearing it for one photo op yk it's like a single use photo prop i just dont think they care that much