Nikon not updating their DX lenses is not really important, as the FX lenses work perfectly well on the DX bodies. Also, with DX you are using the sweet spot of the FX lens and cropping out the outer portions. You just have to pay a little more for the FX lenses. There are also 3rd party lenses that would be happy to take your money.
For those who want a smaller an lighter setup, it is important to these users for Nikon to make dedicated DX lenses. While FX lenses can be used with DX bodies, these are not optimum and will not result in a smaller and lighter setup that dedicated DX lenses can achieved which may be what some DX shooters would like to use.
Visualize this ... a landscape photographer who generally shoots at Base ISO where DX and FX sensor performance do not vary significantly. An FX user can use a D800 with the 70-200mm f/4.0 while a DX user can use a D5200 with a 50-150mm f/4.0 if such a lens exist. Compare the size and weight advantage of the DX user versus the FX user and one will appreciate the advantages of using DX. The higher resolution of the D800 is less of an advantage if multiple photo stitching will be required anyway regardless of whether FX or DX is used.
Because Nikon does not provide such a DX lens option that yields a smaller and lighter setup, the solution to photographers wanting to go lighter and smaller would be to go and use m4/3 cameras and lens system. This option is now a viable option now that the E-M5 and GH3 performs close to the D7000.
This would now fall under wish list but if Nikon also makes a dedicated DX lens that is say 120-300mm f/2.8 VR or 200-400mm f/4 , these lenses could get a lot of interest from bird photographers and from other DX shooters for whom pixel desnity or "reach" is important. In addition to being smaller, lighter, and less expensive, the higher pixel density of the DX sensors and the DX-specific lenses designed to work with such sensors can theoretically mean that such lenses will perform better than FX lenses.
Nikon is missing out on some good opportunities and ceding the market to the m4/3 system by neglecting the DX system.
Edited by Larry, 02 February 2013 - 14:07 .