So you agree..?
That was a pretty contolled test, 'runner. I think the conclusion that most would draw is that the 2MP looks exactly the same as the 12MP when viewed on this site.
Had you made actual prints at a photo lab from these images you would start to see differences on any print larger than 4x6. (smaller than 4x6 and all would look identical)
Had you cropped the images...say down to only a portion of the clam, you would also have seen the differences because cropping is just removing large numbers of pixels. If take an 1/10 area from a 12MP, you're left with 1.2MP....take an area 1/10 crop from a 2MP image and you're left with .2MP. You would probably see the difference between 1.2 and .2 when viewed on this site.
So....again...what you see on this site is the result of great photography...great photographic techniques...but you can't base a megapixel decision upon what you see.