Bill Simmons, writing for Grantland:
After Johnny Carson retired in 1992, David Letterman became the king and stayed the king, even as his show transitioned from antiestablishment to establishment. Leno drummed him in the ratings without matching Letterman’s relevance; he never mattered as much as Letterman did. We forgave Letterman for losing interest over the years, for never filming bits anymore, for clearly not working as hard as he used to, for chugging along because he couldn’t think of anything else to do (and maybe for the paychecks, too). Even an embarrassing sex scandal couldn’t ruin his legacy; he handled the ensuing fallout so effectively that, five years later, people barely remember it.
As Letterman became older and older, those human moments distinguished him. You wanted to watch him after 9/11. You wanted to grieve with him after Carson passed away. You wanted to hear him admit that heart surgery was scary, that he felt humiliated when private demons seeped into his show, that it pissed him off when John McCain canceled on him at the last minute. Candid Letterman was always better than Candid Anyone Else. When Kimmel and Fallon started thumping him in the crucial 18-to-49 demo, Letterman held one trump card: He’s the only late-night host who elicits the same respect from guests that Carson did. Even Jon Stewart can’t say that. We know celebrities appear on late-night shows to promote themselves; it’s part of the deal. They went on Letterman’s show to impress him, to win him over, and that was always the difference.