The idea that Chanel suddenly brought out a less curvaceous figure in 1919 has already been dealt with, so I thought I'd go a bit more academic on this one, if you'll forgive me.
A large problem with the discourse around dress of the 1920s in both pop culture and academia is the feminine/androgynous dichotomy - the idea that the fashion of a particular era is either feminine or androgynous (sometimes "masculine" is the word used for the opposite pole, and in this case, androgyny appears to mean, essentially, "masculinity in female dress"), and that these are two mutually exclusive adjectives.
The trouble is that you can't define anything as objectively feminine, or objectively masculine, because these attributes are determined by socially-constructed roles, which shift with society. What is masculine in one era may be feminine in another, and vice versa! (See: the role of pink and blue in baby clothes.) It's too easy to judge the past by present-day standards in this regard - what we consider masculine, feminine, a combination of both, or neither - rather than to try to see what contemporaries would have pinpointed as any of those choices of adjective.
|"The June Bridal Party is Gowned in White", models by Miss Steinmetz, Harper's Bazaar, May 1922, p. 70|
For the street and for almost all daytime costumes, except those for formal afternoon wear, [Peggy Hoyt] makes the smart woman a youthful, boyish person, given to wearing little velvet costumes with Eton or Fauntleroy collars, trimmed with many tiny buttons and braiding. Sometimes these costumes look as if they had stepped out of "David Copperfield"; again, there is a romantic frill of lace at the throat and cuffs to remind us of the gallant little figure of Sir Joshua Reynolds' famous Blue Boy. ... These costumes are very much part of the modern spirit. ...Even though that slim figure (which related more to young, lissome women than to boys) was fashionable, it's important to consider what was worn over it. Far from there being "a still lingering desire for femininity" represented by a single designer's work, much of early 1920s fashion reflected a stereotypical and historical type of femininity. It was understood that much sporty daywear took inspiration from men's clothing - as had been happening for centuries, with women's riding habits in the eighteenth century, Regency spencers, and Victorian tailor-mades: this was not a new concept for Western society. But eveningwear (and dressy afternoon-wear) continued to be seen as a different beast.
In the evening, this youthful and rather boyish young person Miss Hoyt changes entirely by the simple magic of costume. She turns from the naive Eton collar and short bolero jacket to the full and enveloping skirts of the "picture gown." The smart woman now becomes a romantic figure from eighteenth century Venice, or a gracious feminine lady, flounced and ruffled, like those charming tiny-waisted persons in Godey's Ladies Book. ... She wears silver lace, soft satins, veilings of chiffon. She trails voluminous wraps of lace and rich stuffs and fur about her. She is femininity: she is everything that is gracious; she is romance.
|Peggy Hoyt models, Harper's Bazaar, August 1922, p. 77|
And, of course, one must address the corset. Corsetry and femininity are very strongly linked in the public imagination - corsets equal a curved hourglass shape which suggests an exaggerated form of femininity. There is much discourse about women's bodies being oppressed and confined into an overtly feminine shape, and it is often assumed that removing the corset thus equates to a removal of patriarchal oppression.
|From "Inspirations", Harper's Bazaar, 1916, p.?|
|Vionnet evening gown, pictured in Harper's Bazaar, January 1922, p. 25|
|Ladies' Home Journal, September 1921, p. 153|
* Just a note on this type of dress. It's generally called the robe de style, because a) a few fashion plates label it as such, and b) we fashion historians love having specific names for specific styles of dress (as well as specific traits to pin to specific designers). But in the research I've done recently on the 1920s, it's become fairly clear to me that the vast majority of people and designers and fashion editors would refer to it as the "bouffant look"/the "full-skirted silhouette" or simply call them evening or afternoon dresses with various adjectives such as "romantic", "nostalgic", "old-fashioned", &c. Robe de style is not an anachronistic term, but it seems to me that calling every full-skirted 1920s dress a robe de style as though they were seen as unrelated to "ordinary" dress is not true to history.