Right there in the third paragraph of "To Build a Fire," the narrator tells us all about the "trouble" with the man, which is that he is "without imagination" (3). Now out in the cold Yukon, you probably don't think that having an imagination is going to help you much. But the timing of the narrator's comment suggests that this lack of imagination is a significant shortcoming that will lead the man to make foolish decisions. As readers, we must wonder what good it would do the man to think deeply about the vast wilderness around him. After all, the guy's not a writer. He just wants to go get some bacon! So why suggest he's foolish for not having imagination? This is a question we leave to you, dear readers.
In this story, the narrator makes a big deal out of the fact that the man has no imagination. But the Yukon wilderness couldn't care less. He's just another warm body it can freeze.
London makes a connection between the man's lack of imagination and his unwillingness to listen to other people's advice.