The digital sensors' inability to utilize all the light passing thru wide open apertures - unfortunately - is not limited only to f1.2 lenses...Not a subject many of us would like to hear/think about ; so better cut short :-)
The whole "sensor tweaking iso values" I believe it just a normal expected effect of of moving to digital. When it comes down to it, if the iso is bumped 10, 25, 50 but the image quality doesn't suffer, the ideology argument of companies hiding it gives way to the practical real world use where it doesn't matter. I don't like seeing it, but if it took a huge computer with many instruments to find something the human eye can't - I don't see the point on dwelling on it.
Nikon exists to make money. It will produce any lens it feels will sell in sufficient quantity to reap a profit from the development and production costs.
I couldn't agree more. They are there to make money - not keep everyone under the sky happy.