Why is the futuristic setting crucial to the "The Hunger Games's" story line ?
The answer to this question needs to be regarded as one of a subjective nature. Some readers may not think that the setting needs to be placed in the future and, therefore, will disagree with my answer.
As for why I believe that the setting needs to be placed in the future relies on the targeted audience. It would be very difficult for readers to relate to the story given the action in the story is not something which they have had experience with. The games are harsh- to allow readers to engage, the author must place the action in a place where it could happen.
It is important for an author to engage a reader. While the novel is fiction, it helps that the setting is futuristic given it allows readers to create an image in their mind about the story itself.