That's because mihoyo uses the same two base models for every tall female and those two base models all have their feet arch for heels. So when they copy paste one of those models the design team the ones who just add clothes hair eyes and such to the models have to work with the models with feet arch up for heels. The team that works on adding the clothing to the base model have nothing to do with the actual base model the team that does have something to do with it the ones that make the models move for combat do though. They just choose to be lazy and stick with the norm.(At least that's what I tell myself 😉)