One social norm that has changed drastically since the turn of the century is acceptable appearance for women. The idealist would probably attribute this to greater freedom for women, not just in apparel, but in all aspects of their lives. The materialist would most likely attribute this to drastically increased selection of apparel, as well as an increase in income for women.

Well, I believe they go hand in hand. If the acceptable appearance had not changed, you would probably not be seeing the range clothing that is available. I think however, the best explanation comes from the materialist explanation - mainly women have more income, and this gives them greater control over their choices and greater demand in the clothing market.