The significant aspect about the namelessness of the man is that the author wants the message of the story to apply to everyone, not just the main character.
The namelessness of characters is a literary device that has been implemented for centuries.
One way to employ this literary device is to have an anonymous narrator who plays no part in the story, but who just acts as an observer telling the tale.
Novels or stories with nameless protagonists are dystopian, however leaving a character unnamed also shows that he or she is experiencing a personal crisis of identity, and the reader focuses further on how the character is affected.