To me, the finished product could have been entirely too 'real'.
To even the less cynical among us, the periodic struggles of humankind, defeats followed by triumphs, war followed by eventual peace, are daily life, as are the inevitable slides back to the darker times. People are seemingly
bored by peace, and I think
NS just brings that fact to the forefront even among the noblest, most 'blessed' kingdom of Men in Middle-earth.
This brings to mind another
recent thread that explored the reasons for reading Tolkien.
The New Shadow would have possessed an entirely different spirit than the other Middle-earth centered works. It would ground one right back to this world after 'living' in another, and wouldn't that somewhat taint the entire Tolkien experience?