No point in having twice as many pixels? I disagree, especially since I have a 46" that shows real difference between the two.
Rush HD has quite a few 1080i broadcasts and a few other HD channels we have send in 720P, the crisp and incredible picture on Rush HD is a lot better from any sitting distance.
I've also seen Blu-ray movies in both 720P and 1080P, the difference is considerable, like it is when you're playing on the PC. All my games look a lot better in 1600x1200 than they do in 1024x768, there's just no denying it.