I was really surprised to find out (because this post piqued my curiosity) that the Star Wars prequels were shot in only 1080p. I'm really surprised that that didn't look atrocious on the big screen. Hell, that's like half a centimeter per pixel.
Its only a few cinemas that are capable of 4k (thats 4098x 2160) and even fewer films released in 4k.
Since they were switching to new hardware anyway, why didn't they just make the CCD the shape they actually wanted, rather than relying on this weird archaic workaround?
Same idea as recording individual audio tracks at extremely high quality. The final mix ends up sounding better than you might expect.