I enjoyed David Letterman for many years, became a fan way back at his morning show . Loved the irreverence, and the silliness of "Stupid Human Tricks" and the like.
"Irreverence" means nothing anymore, of course ['transgressiveness' is the rule rather than the exception], because you can't have a comedy of manners when manners no longer exist.
Silliness [Sid Caesar, Laugh-In, Monty Python, Hee-Haw, Will Ferrell] will never go out of style, though. But at some point Dave abandoned silliness, which is fun, for dadaism, which is nihilistic. By the '90s, I remember mocking Dave's comedy laziness, that he could yell, "Pork Chops!" and the sycophantic audience would howl in delight.
Sure enough, only a few months later, on the back of an LA bus I saw Dave in an ad for Late Night that read
HONK IF YOU LOVE PORK CHOPS!
True story. Don't remember if I honked or not, but I wished I'd have tried to get a gig writing for Dave. I was clearly a comedy genius, just like him. Letterman clearly gave some people some joy--or its equivalent--but unlike Carson, I think he left us more cynical, less informed rather than more, harder rather than softer.
His interviews were indifferent, and when they weren't indifferent, they became undisguisedly partisan. Johnny Carson brought America together the next morning around the water cooler. If anyone asked "Did you see Letterman last night," the answer became increasingly, Sorry, I gotta get back to my desk.
Strangely enough, Dave, I'd still rather watch you than Jimmy or Jimmy [Fallon, Kimmel, respectively] because I'm a kind of edgy guy myself, but I'm glad to see you go. The Jimmys are more delightfully silly than you ever were, and they're less corrosive to the culture. Sarcasm has its place [I loved Frank Zappa], but it should be a very small place.
Epilogue, more to come: Dave's successor, debating the theology of the Eucharist with a Pulitzer-winning Catholic dissident and kicking his ass? Stephen Colbert, now, there's an interesting fellow.