Steve Mitchelmore quotes this passage from Reiner Stach’s biography of Kafka:
[Kafka] demanded much more from his texts than formal unity; he sought a seamless linking of all motifs, images, and concepts. Beginning with "The Judgement," he was generally able to achieve this unity in the stories he completed. These writings leave no narrative residues or blind alleys. Not one detail of Kafka’s descriptions, whether the color of a piece of clothing, a gesture, or simply the time of day, is merely illustrative. Everything carries meaning, refers to something, and recurs.
He then asks: "Curiously, one might compare this with the detective novel. So why do I loathe that kind of book?"
I'd volunteer this answer: For the most part, detective novels create a "seamless linking" that's meant to point us forward, to the solving of the crime. "Motifs, images, and concepts" are the means to an end, interlocking parts to a puzzle that is finally assembled in its entirety, only to then be disregarded except insofar as it gives us a finished picture--mystery resolved.
Kafka's fiction evokes a unity that points only to itself, to its existence as an aesthetic creation. Kafka directs us not to the resolution of his metaphysical mysteries but to the impossibility of such a resolution. His "motifs, images, and concepts" are ends in themselves, interlocking parts of a puzzle the signficance of which lies in the process of their assembly, not in the finished picture, which can never be brought quite into focus.
Detective novels explore guilt--the specific guilt of specific characters in specific circumstances. Crimes have been committed. Kafka's fiction also explores guilt--the guilt of being alive, of feeling one's existence cannot be justified and will never measure up. Crimes have been committed before we were born, but we must pay for them nevertheless.
Once a detective novel has been "consumed," the reason for its being goes with it. How many detective novels bear re-reading? (There are exceptions, Raymond Chandler for one.) Kafka's novels and stories must be re-read because they can never be consumed. They're poison to the system. They leave their readers as perpetual hunger artists. The next time we read, say, The Trial, perhaps we will finally perceive it for what it is, not ask it for answers to questions it never promised to provide.
If "everything carries meaning" in Kafka's fiction, it is meaning that ultimately undoes itself. Everything portends, nothing is settled. Detective novels assure us that things will be settled, that knowledge is possible. Our world, although brutal, makes sense. We exchange the one for the other. Kafka tells us that this a delusion. The world may be cruel, but it also makes no sense.