Village Idiot said:
More MP give you a larger image that's easier to work on in post. It's an extreme example, but try doing a complicated edit on a photo that's 24 MP vs. the same photo that's 1024 on the long side.
That is a simply ridiculous example V-I. That comparison is akin to saying, "an elephant outweighs a house fly." Yeah, no chit Sherlock. 24 MP versus 1024 pixels??? WTF????
As Blair Wright pointed out, and as I pointed out, megapixels are overrated by many people. Thom Hogan has now tested four different Nikon D3x bodies; The D3x has more MP than Canon's top body, and is the highest-resolution d-slr on the market. But I challenge anybidy who says, "more megapixels is better" to go to the review, and scroll about 3/4 of the way down and look at the side-by-side comparisons of 12 MP versus 24.7 Megapixels when the D3 images are up-sampled to match the size of the D3x images...
It's really simple: 12 MP on FF is about all "most" professional-grade lenses can resolve. And, when using a truly superlative lens, like the 200mm f/2 VR Nikkor, the D3's 12 MP images can be up-sampled to produce images that look ALMOST THE SAME as D3x images...
If a guy wants more megapixels for critical retouching and spotting of images, which I have done, it's easy enough to up-rezz the image in software and get a nice, big file to work with.