I probably should have opted to include books if I wanted to cast a wider net. I’ve enjoyed the books of Ross MacDonald, John D. McDonald, Rex Stout, Richard Parker and prolly some others, and I know there’s a lot more detective novels than detective TV shows.
Parker is given credit for singlehandedly reviving the detective genre with his Spenser novels, except I haven’t seen a resurgence of good detective fiction of the hard-boiled variety since then.
However, I really don’t think the genre has died because of it’s implausiblity, it was always a kind of implausible genre. I suspect that genre has come about because of a change in our understanding of crime. Back in the 40s and 50s, crime was considered a moral flaw of a personal nature: no matter who you were, what your background was, it was because you as an individual had some defect that was manifesting itself in crime, and even if the defect was due to some horrible maltreatment you received at some point in the past, it was your personal flaw that made you “turn to crime” as a result of it.
Now we see crime as more relative, and the act of chasing down the criminal as not necessarily something noble and good, but more the dogged rendition of inexorable “justice” to someone who may or may not deserve it. We also see it more as product of social class than individual moral flaws. Thus the rise of police procedurals like Law & Order and CSI where the cops are fighting cartoonishly evil drug lords and dealing with pathetic junkies and ordinary people who’ve been pushed over the edge by circumstances. They’re not moral arbiters dispensing rich, steaming bowls of fragrant justice, they’re civil servants trying to navigate a moral morass without becoming damaged themselves.
The classic PI is conceived of as the heroic outsider, the white knight who navigates the land between the seamy underbelly of society and the world of middle and upper class white people (OK, in the old days that would simply have been “decent folks”) meting out justice and solving problems that the police can’t or won’t solve. Thing is, solving ordinary crimes won’t do it, that’s not where we find evil.
Plus, we may have become too fractured as a society to have a consensus about what a white knight does. Now I personally would LOVE a TV series about a detective who spends every week investigating, beating up and shooting rich investment bankers, war profiteers, corrupt politicians (basically, almost all of Congress but especially the Republicans). “Hit 'em again, Franken!” I’d yell, watching the show, “Now gut shoot that investment banker … make him crawl through a pool of his own blood!”
But others, I suspect, might find the content, or the target of the private eye’s investigations, disagreeable.