Robert Rorke

Robert Rorke

TV

Why did David Letterman wait until now to say goodbye?

A typical late-night with Jimmy Fallon might include the host doing the “mom dance” with First Lady Michelle Obama or impersonating Bruce Springsteen — with a cameo from the Boss — on a hilarious sendup of “Born to Run,” the lyrics reworked as “Gov. Christie’s Traffic Jam.”

Over on Jimmy Kimmel’s show, the host might reveal that he asked parents to pretend to eat their kids’ Halloween candy, then upload their crestfallen reactions on YouTube.

What’s David Letterman up to, most nights? Same old, same old. In March, Emma Watson came on, and Dave, now 66, told her how his son was going to read the “Harry Potter” books. And then she promoted her new movie, “Noah.”

Did Letterman pick the perfect time to retire or what?

With the late-night television landscape undergoing its biggest and most exciting shift in 20 years and ambitious hosts carving out their own niches, Letterman suddenly looks like the odd man out. He was once the cutting edge of the talk-show genre — his unbridled irreverence made him a media favorite — but now he’s no longer part of the excitement.

After more than 30 years on the late-night circuit, it’s bound to happen.

The Jimmys — Kimmel and Fallon — and Seth Meyers are making their own inroads much as Letterman and his lifelong rival, Jay Leno — who was forced to leave his NBC show in February — did when they were younger, more ambitious men.

The Jimmys: Kimmel and Fallon.WireImage

The new late-night hosts have made their shows more interactive with viewers, and, in the case of Fallon, filmed full-scale production numbers, such as his recent, joyous clip of Kevin Bacon re-creating his number from “Footloose.” These build the kind of social media buzz that is the new proving ground of any show’s success.

The last time the notoriously reclusive Letterman made headlines was in 2009, when news of his liaisons with female staffers, including his former assistant, came out into the open, shortly after his marriage to longtime girlfriend Regina Lasko. A mortified Letterman handled the situation diplomatically, apologizing on-air, but the scandal cast him in a new, unflattering light and couldn’t have been good for workplace morale. The late-night king and media darling was the subject of the news, not the newsmaker.

Letterman had begun to lose his edge in the early years of the 21st century when Jon Stewart’s “Daily Show” started scooping up all the Emmys for Outstanding Music, Variety or Comedy Series (Stewart had a 10-year streak, from 2003 to 2012).

Jon Stewart is the host of Comedy Central’s “The Daily Show.”Kevin Fitzsimons

Still, Letterman’s legendary status casts a long shadow. When he began his talk-show career in 1982, following “The Tonight Show” with “Late Night with David Letterman,” he brought a sense of mischief and irreverence to the gentlemen’s circuit. His goofy new skits — including Stupid Pet Tricks, where dogs drive cars or recite “poetry,” and the Top 10 List, which counted down, in an increasingly absurd fashion, the news events of the day — made him famous and earned his show nine Emmy Awards over the years. His edgy humor attracted the same demographic sought today by Fallon and company: 20-somethings looking for young comedians they can identify with.

He switched networks in 1993, after losing “The Tonight Show” to Leno following Johnny Carson’s retirement. For the first three years on CBS, Letterman beat Leno in the ratings — a personal victory — and the comedy had a liberating, anarchic spirit.

When he took the show to San Francisco for a week in 1996, he sent a crate of tennis balls and then watermelons rolling down a slanted street. “Release the melons!” he commanded with demented, gap-toothed glee.

In another skit, from 1997, he commandeered a drive-through Taco Bell and told customers he was Dave, the manager, and their orders would take 90 minutes to prepare. When one customer scolded him for being rude, he said, “Both of my parents were rude and I guess I get it from them.”

Those were the days, and there are countless moments — brash, bold and brilliant — like this. But as he got older — and richer (his salary was estimated to be $32 million in 2009) — Letterman turned a great gig into a desk job, and the spark went out.

The Top 10 lists were fine and the Stupid Pet Tricks still cute, but Letterman didn’t seem to have any interest in doing anything crazy anymore. The stars came out, sat down and Dave did the interview. Then he introduced the musical guest. That’s a wrap.

So, are we in for another year of this? TV legends and long-in-the-tooth TV shows take longer and longer to say farewell these days. Barbara Walters announced her retirement from ABC News, coming May 16, a year ago.

Letterman’s longtime fans, many of them aging baby boomers, have every right to get nostalgic about the old Dave, the guy who would pull any stunt for a laugh. In a perfect world, he would take his final year to recapture some of his brazen, bygone glory and give us some of that vintage Letterman. Not the one we can only find in YouTube clips.