Not that it makes it acceptable, but Vaan from the same game also had some armor deficiencies. Also, that game gave us Judge Drace, who has some of the most comprehensive armor ever seen, let alone of a female character.
So remember how some people try to claim that sexy armor is just a thing we have to live with because of the mythical “Asian culture“ ? And franchises are only capable of targeting one demographic so must oversell to it?
Though personally I think if Fran had been issued or stolen Vaan’s pants, that would have been a remarkable step forward in progress.