When CSI first premiered, it was the "not your average cop show." Prior police procedurals were all about detectives knocking on doors, dragging suspects into "the box," catching them in lies, entertaining us with the art of interrogation and so forth. "The Lab" was either fully offscreen in the form of a "state crime lab" you sent stuff off to, or represented by a nebbishy pseudo-cop who appeared only long enough to spirit away fingerprint evidence for processing behind the scenes. The essential conceit of CSI, that cases are really solved by the geeks who chase physical evidence, and who (initially) were not even permitted guns or badges, was at the time revolutionary.
Over time, a synthesis has emerged. The assorted CSIs have adopted most of the conventions of older police procedurals. The original still occasionally nods to the idea that their characters are not actual police, though it much more frequently overlooks that in favor of the drama of having a main character charge into a dangerous situation with gun drawn. The follow-on shows just gave up on that idea altogether and made their main characters real police, and their jobs a completely impractical hybrid of lab technician and traditional homicide cop, to the extent that the pure homicide cop supporting characters in those shows often seem superfluous.
At the same time, newer cop shows have liberally appropriated the tropes of CSI. It was as if writers "knew" how police procedurals worked because we've all seen Dragnet, but it took a show like CSI to make them sit up and notice that the procedure itself has changed in the last forty years. Even though CSI itself is largely science fiction, forensic evidence is now understood as a major part of how crimes are solved, not a supporting plot device to be dropped at the end of an act break just to give the stalwart hero detectives the next door to knock on.
So in the end, cop shows are just as formulaic as ever, but CSI at least deserves some credit for bringing a much needed update to the formula. Now we'll just be stuck with this formula for another forty years until somebody notices that the real heroes are the brave artificial intelligences that correlate collected trace evidence with deep mining of suspects' Internet traffic.
