Feels like a lot of you are missing the point. This wasn't a retelling of War of the Worlds with World War I as the setting. This was a retelling of World War I, with an alien invasion as the setting. With a twist ending that gives the whole thing a more potent meaning than "cool mockumentary".
*Shrug* Just a tiny detail that isn't really worth arguing about in my opinion. Because either way you look at it, it was at least heavily inspired by it. And either way, it's really well done.