I think the margin is not as reflective of how people are primarily using the camera, but more about how the poll was written.
I use my D800 100% of the time I am in studio and probably for about 50% of my sports shooting. But I shoot sports 10x as often as I do studio work, so I have to say sports is primary based on how the poll goes.
I think your poll is skewing because a great percentage of people here in the D800 forum are landscape shooters. Most likely shoot other subjects as well, but the preponderance of their work tends to be in one area, thus the primary use of their camera has to follow.
>I'm surprised at the margin too. Three times as many >landscape and wildlife shooters as all others combined.