Although technically true, the cropped image would lack any useful sharpness or detail if cropped down to 8MP for example. I shoot with the 36MP D800 and for all that resolution, if I fail to take a sharp image (bad glass, light, atmospherics, etc). I can't crop it usefully. It's a myth to believe that massive means more cropping.
I could take an 8MP shot on a full frame sensor with great glass in front of it and shoot an image that would crop better than Nokia's MP beasts.
I'd prefer apple to improve the quality if the glass, dynamic range and other technology. They can process images with better results if there are only 8MP to process.