In an interview with George Lucas, he said that he wanted everything in Star Wars to look like it would in real life. All worn, with scratches and repaired parts. Plus, not everything worked perfectly, such as the various issues with the Millennium Falcon.
This was distinctly different from prior science fiction pieces (movies or TV shows) where everything is perfectly clean and never malfunctions.
Was this the first time this was done in a movie or even TV show?