Roy Jinks' "The History of Smith & Wesson" states that the first stainless steel handgun, the Model 60, was initially made with a bright polished finish on the frame, barrel, cylinder hammer, and trigger. It was difficult to manufacture and law enforcement didn't like it (I guess to reflective), so S&W went to the satin finish in late 1966, at about S/N 490,0001. The satin finish became the standard finish for S&W's subsequent stainless steel handguns.
I sort of expected that, when S&W discontinued nickel in about 1992, they might offer a high polish stainless finish as an option for folks who like the shiney guns, but of course they didn't.