Jesse Hassenger, Guardian
And just what is a concerning nail?
Is there an unconcerning nail to make the comedy inside less dead?
The Grauniad on this topic suffers from the same thing Colbert suffers from: seriousness where it doesn't belong.
In becoming political, comedy has become serious, while at the same time the leaders are no longer serious enough. No one wants to get ready for bed being reminded of that.
Back in the day when the population was a lot smaller, Johnny Carson regularly kept 15 million people awake laughing. Colbert today is lucky to get 3 million, in a much bigger country.
Carnac the Magnificent was funny and enduring. The rip-off from Steve Allen was in its turn ripped off from Carson by Howard Stern. And Wikipedia redirects you to "Late Night with David Letterman" from "Stupid Pet Tricks" for a reason. People remember that stuff.
Colbert belongs to a small minority, the jaded left.
Put funny back on late night, and people will stay up to watch it.