Why 'Maron' and 'Louie' miss the mark
Both of them are, at heart, stand-up comics. They're neither trained actors nor comics who have had the benefit of small, easy TV and film roles to make them more comfortable in front of a camera. In other words, they're both self-consciously pretending to be themselves in an artificial, stylized context.
Louis CK's best jokes are all about how sad, miserable and pathetic his own life is. The humor comes from his own awareness of such--hearing him tell the story of a particular awkward moment in which he was humiliated is gratifying because his telling of the story is perfect, just as we would expect from a journeyman stand-up like him.
The same goes for Maron, another brilliant stand-up comic who can make killer jokes out of his own sad, miserable life. Every time he weaves a tale of another relationship that went awry, we not only feel for him but want to laugh because he's aware of what an ass he was and how the entire situation was absurd to begin with.
When this is translated into a TV show, which has its own literal, two-dimensional conventions of storytelling, the magic of humor is lost. The subjective voice of the comic gives way to the tyranny of the image--all we can literally see is the sad, prosaic situation the character is in. We're robbed of his authorial voice to put it into a tragicomic context, to show it from an outside perspective in order to collectively mine some greater, funnier truth from what would otherwise be just a brown heap of life dumped in front of us.
"Beethoven had his critics too, Keith. See if you can name three of 'em."