Of course this is only a concept for consideration with a digital SLR body since digital cameras with built-in lenses have lenses designed to cover a smaller area. Cropping out the edges of a poor performing lens may be a nice thing for some people, but for a good lens there would be no benefit.
Whatever good you might find in using only the "sweet spot" of a lens, I find the drawbacks much more problematic. The D100 would take my superwide 18-35 zoom and cut the wide perspective down to a puny 28mm equivalent. I'd rather have the full field of view with whatever edge softness that may imply rather than lose the characteristics of an expensive lens. I look forward a couple of generations to full frame digital SLR bodies that offer all the flexibility that the 35mm lens systems have to offer.