Seeing creators resort to "in-universe" explanations for their own creative decisions is really frustrating. Characters are not real things you're transcribing into the universe with your reality-bending, creativity powers. They are a series of decisions made throughout a given story. The idea that they exert a will that could somehow change their visual design is dumb. Cortana is not semi-nude because of some immutable character trait, she's nude because she was designed that way by an artist looking to achieve a goal (and yeah, titillating a largely male audience is part of it, but so is a strong contrast with the Chief). She was also designed in the late 90s, and Halo's art direction didn't really come into its own until Halo 3, by which point they were kind of stuck with the design.
Own that shit. Don't hide behind shitty writing and extended universe guff. Be Kamitani. He doesn't give a fuck.