One of the issues that I haven't seen raised, although implied (with the drawer full of WA lenses) is the fact that a lot of photographers, I imagine, shoot film and digital. Whether it is the new 14-24 or the older 17-35, the lenses will give different results if I use them on any of my "FX" film cameras compared to using it on a DX camera (in my case, D200). The introduction of FX DSLRs allows this difference to be resolved.
I don't want to go out and buy a WA DX lens just for my D200 which I can't effectively use on my film bodies.
For me, and this is the real issue, the new FX bodies are important. I say this is a real issue in that I read a lot of comments (on both sides) along the lines of: "this is my situation, and I will therefore extrapolate to everyone".