The Kodak Retina I hearkens back to the days of vest pockets. While vest pockets and vests themselves fall in and out of style, the Kodak Retina I remains incredibly stylish all on its own.
The Retina series of cameras is right up there on the list of most influential 35mm cameras for a couple of reasons. The biggest reason being that it was the Kodak Retina that helped introduce the world to the Kodak 135 daylight-loading single-use film cassette, otherwise known as 135 format film... otherwise known as 35mm. Many cameras, prior to the Kodak Retina, used 35mm film, but this was generally film cut down from motion picture rolls and hand-loaded, either directly into the camera or into reloadable cassettes that were often proprietary to that camera. Kodak's innovation was the design of a cartridge that was factory loaded, simply needing to be popped into the camera by the photographer. This cartridge was further designed to be compatible with the Leica and Contax cameras of the time, increasing its popularity; but it was Kodak's own Retina line of cameras that primarily drove the rise of the 135 format.
Additionally, Kodak Retina cameras represented incredibly well made, durable, and high quality cameras that were still much more affordable than a Leica or Contax camera. The Retina line was meant to be more accessible to the general public, while still competing with Leica and Zeiss Ikon's Contax cameras. In many ways, the Retina succeeded; their production run lasted from 1934 until 1969.