I think there's an argument to be made that the D800 can degrade your photography. When you were shooting with Coolpixes you didn't worry about lenses or tripods or cable releases and you didn't spend time pixel-peeping. You tried to frame and expose things that made good photographs, and you proudly displayed the stuff that was good. But now, with the D800, you pass up a good photograph because you have a less than top-of-the-line lens on the camera, or you left your tripod back in the car, or you can't find your cable release.
If you go out and shoot the same way you used to shoot when you had a 12 megapixel camera in your hands (In your hands? Horrors! Where's your tripod?), then in post-processing you reduce your 36 MP to 12 MP, you're going to have at least as good results as you used to get from your 12 megapixeler. Actually, better, because the DR and color are better.