By the way, if we compare it to the analogue days: 36 mm x 24 mm film is estimated between 4 and 16 million pixels depending on the type of film used. Source: http://en.wikipedia.org/wiki/Digital_versus_film_photography
At the top end of the estimate, the difference is even smaller.
My partner in Building Panoramics was in at the dawn of digital imaging business so I know a little about this. I haven't looked at the wiki link, but to all intents and purposes 6 to 8 mp is about equivalent to good 35mm film in terms of resolution. You can scan more meg but you end up recording grain.
Try taking 5 shots at 1/20 on a 35mm focal length hand held with no support. You will inevitably find that one or two frames have IQ damaging blur when viewed at a reasonable enlargement. ( For me it would be four out of five). You may say these are acceptable odds but when that one frame is important it becomes unacceptable.
I read many people on here claiming that the new IS primes are aimed at video, but how many people are 'serious' movie makers wanting these primes compared with the amount of still photographers ? Also when you look at the Canon cine focal length lenses for FF you would have to ask why a 24 and 28, and where are the 50 and 85 ?