Yes, Joan was beautiful and very stylish during the 40s, but in 1949 she was 39 and that was often the kiss of death for an actress as it relates to being a romantic lead \ love interest of the leading male (who was often in his late 40s or even 50s!). So I can hear the studio suits saying she should feel lucky that James Mason (who was 40) was sexually interested in her in The Reckless Moment. I.e. if you don't get these mother roles you get no work at all.
Love that hairdo line. Yea, many of those 50s hairstyles made the women look dowdy. E.g. Jane Wyman. She was featured yesterday in a film released in 1944 and she was very beautiful (and what legs), but while she was a big star during the 50s her look was a lot less appealing.
Yes, I agree with your point about 1950s hairstyles. Women's fashions changed in general, with longer and sleeker dresses.