Then there's the resolution. The image resolution has been increased far beyond current HDTV standards. The images in The Hobbit will have 4 - 5 times more pixels than a standard 1080p HD image. So the image will be immensely sharper, too.
Even most digital presentations far exceed 1080P, and film stock definitely does. 48FPS is not about the resolution of the frames, but the number of them. The 24FPS version will have the same resolution, just fewer frames. The 4K is completely independent of the 48FPS. Most BluRay discs masters are 4K transfers downgraded to 1080P.
That said, I agree with all your points.