if you put a grid pattern on the curved screen, how many 'seats' in the house would allow the viewer to see that grid without obscuration? Even the central sweet spot cannot be too high or too low, without seeing the straight lines begin to curve out to the sides.
I can only imagine how this would look with panning scenes... my old Panny plasma had a 'stretch' mode to fill the wide screen with a 4x3 image, and it was hideous during pans - it looked like it was projected onto the side of a soup can.
People say 'but it is such a subtle curve you won't notice these things'... so DON'T BOTHER CURVING IT AT ALL! I buy a TV to use as a monitor, and the perfect monitor would have no base and no bezel, and just let me see the image uninterrupted.