You have to wonder what lenses are being used in these cameras, good abberation free glass is very expensive so if they are spending more on sensors it could well be at the expense of the quality of the lens. As it stands, most consumer lens cant actually resolve much detail above what a 6mp sensor can resolve, a lot dont even resolve anywhere near that so even if you had 60mp you will only get the detail that you would with a 4mp if the lens is not up to much.