From the beginning (when I proposed this design to Butterick), I've always called this "The Draped Wiggle Dress." When I think of the classic wiggle dress, I usually think of something in wool, with sleeves and a higher neck. (Like the one in my book!) But then there's also the cocktail-style wiggle dress, in a fancier fabric. The genesis for this one was the green dress Joan wears in a Mad Men poster.
I loved the side drape on the dress she wears here. From this point, I started looking at other designer dresses from the era, particularly the work of Peggy Wood. It was her use of little raglan sleeves and bodice draping that inspired by own bodice design. Here's an example of a typical Peggy Wood bodice:
Tomorrow I'll write about the construction of this dress. While it looks drapey and soft, it has a serious inner structure, including steel boning, underlining, and a grosgrain waist stay!