John Lennon said it best... it's just rock and roll with lipstick on. I think the image of the whole glam concept had a lot to do with publicity. Even if glam worked in some ways to advance society's acceptance of ambiguous/risque concepts, I don't think it came about with the intention of starting some gender revolution. Ziggy in particular seems more like a very clever satire about the absurdity of rock/"rock messiahs."