And you are right, of course, in that ios allows most people to do the things they most care about very easily-- that's probably the takeaway. If you do that, then, apparently even if the other stuff is hard, people will probably figure out how to do it when they need it. Somehow.
Android devices on the other hand, need constant fiddling. My Droid would barely last a day with everything turned off, and with wifi, etc. turned on, it would die after only about 6 hours.
Disclaimer: I don't own an iOS device, so don't know how intuitive it might or might not be.
The only reason to turn off the cell radio but not the wifi radio is to conserve battery, which again puts you well outside the use case of the typical apple user.
In my experience, this is rarely enforced.
(In fact, I just got off a plane, and the announcement is "electronic devices must be off, not in airplane mode. that's for after we're in the air.")
I think that you overstate the importance of turning off wifi and bluetooth. Those are power user options, for sure. When you're trying to conserve battery power, you're trying to streamline how you use the device, which to me, smacks of 'power user'.
The flipside to that argument is that it is ridiculously easy to browse a web site, check your email and play Words with Friends and Angry Birds. These are the things that the majority of people care about... not whether or not a given physical interface is active or not.