I think that the 1920s use of cinema was primarily driven to further drive the mass consumerism that defined "the roaring '20s."  The 1920s cinema featured larger than life stars on screen that would highlight glamor and a sense of beauty that was concurrent with the "jazz age" lifestyle.  Greta Garbo wasl part of this, as was Jean Harlow after 1928.  The silver screen was enhanced by beauty and style.  After the Al Jolson talkie in 1927, this helped to influence the drive that was already intrinsic to the time period to represent a sense of the mass consumerist appeal where surface beauty and materialism were a part of where individuals found social acceptance. Before that, cinema represented a fantasy land with perilous adventures and magical escapades with star who became social symbols of connectedness and possibility.

Cinema became a representation of this where wealth, the trappings of material prosperity, as well as materialism all converged in the images on the screen.  Cinema became a vehicle where individuals could find escapism and inspiration to become a realistic version of these screen idols and the world on the screen.  Cinema was no longer something that individuals felt were a realm impossible to attain.  Rather, the culture of the time period helped to enhance the idea that individuals could actually be like that which they saw on screen.