When you buy a high end card, you're buying the development time required to enable advanced features, you are not buying hardware; the silicon simply doesn't cost that much to produce. Most people do not want or need these advanced features, nor do they want to pay for them. The alternative environment has everyone paying $2000 for the same card and much fewer sales vs. premium users paying for premium features, and everyone else getting what they need at a much lower cost.
They're not just spending the development time on advanced features. NVidia appear to have intentionally crippled stuff like data transfer speeds to and from the GPU on their consumer models (but only for OpenGL/OpenCL and DirectCompute - you still get full speed when doing the exact same thing through DirectX) on the basis that it mostly only screws professional users.
