Hi Bernard - not to belabour - but I would think the auto-ISO feature becomes desirable EXACTLY BECAUSE these cameras perform so well at high ISO - it makes it feasible to allow the camera to select a high ISO when low lighting forces you out of sustainable shutter speed and aperture.
I see, that is indeed one way to look at it.
Coming from a fixed ISO system, I have been looking at it differently though. I believe that most users who do not have autoISO typically set the ISO on their camera high enough to ensure that they will get enough shutter speed in the average conditions they will encounter at a given moment. I don't think anyone really changes ISO manually that often in street shooting situation, but then again, it might just be my way of working. This impacts negatively all the images where a lower ISO would have been sufficient. In other words, autoISO enbales a camera with avergae to poor high ISO to only show this weakness in these images where there is no other option anyway.
This really depends on how autoISO is used and implemented though. On the body I use, you can set a minimum shutter speed that you want to preserve, and the camera will use the lowest possible ISO making this possible. It will only lower the shutter speed further when the highest authorized ISO is reached. Nikon developped this to limit the negative impact of the then lowesr abilities of the d2x compared to its Canon competitors.
Anyway, 2 ways to look at the same thing. :-)