Lucas’ main inspiration, Flash Gordon had a lot of scantly clad damsels in distress and even Flash himself was bare chested almost as often as Captain Kirk. The 1930’s serials reflected this, (as much as the production code allowed at the time) and the 1980 movie made it more overt, as did the Filmation version. The animated Princess Aura was pretty smoking hot for Saturday morning tv!

I don’t know if Lucas was asking McQuarrie to draw Leia in skimpy outfits, but Carrie is on record that the infamous metal bikini in ROTJ was George’s idea.