Why produce a top flight APS camera? Why object to the top camera being a
D90 "upgrade" with a FF sensor and not a D300 upgrade with an APS sensor?
Now that APS has hit 24 megapixels, it has to be considered it offers the
best option for wildlife photography, outside of the D800, but more
importantly, it does give lenses greater "reach" so somone can shoot
wildlife with a relatively portable 300mm lens versus a much larger and
heavier and much more expensive 400mm lens.
Linear resolution comparison of a 24mp APS and a 300mm lens and the D800
36mp and a 400mm lens gives APS about a 8% resolution advantage, so for all
purposes, they offer the same resolution. However weight savings of the
camera-lens combos gives the APS a distinct advantage.
In fact, it may be possible that true resolution comparisons would show
even greater advantages due to higher stability offered by the lighter
combination, either on tripod/monopod or off. It would require testing to
determine that.
I wish they'd release a 40mp APS sensor for low ISO, high resolution work.