Forcing or pressuring companies to promote women based on anything other than merit is simply a different form of prejudice. There's also no point unless there are substantive changes in company policy and corporate culture.
In the 1980s, there was an "understood" dress code. Largely dark suits with skirts to the mid-calf. Demure dresses just started. Forget about cleavage or bright colors. The one bright spot -- nothing about the kind of make-up one could wear.