They did it so that next year's tv will be 2160 hz!
Very interesting btw Alan. The 'sweet spot' as you discribed it reminds me of my first foray into High Def.... my 65 inch rear projection Toshiba 1080i wide screen. As long as you sat directly in front of it, the picture was just about as good as any LCD, LED, Plasma, Laser or anything else out there. But move even a few inches to the left or right and things started to look a bit darker. And you could pretty much forget about sitting to the side of it altogether, you couldn't see much at all from 45 degree's on back.
Sounds a bit like this new technology. 10 years from now we'll all be watching 3D tv without the need for glasses.... hip, hip, horray!!!
