How do you know who all the other passengers are observing you photographing their country as you fly into it? All they would have to do is point a finger at you in Customs, and have your camera inspected. It's all very well disregarding these rules and you will get away with it 99.9999% of the time, but the rules are there, and it's the other 0.0001% (?) that will get you. For example- fly to Moscow and snap away happily en route? Try it to Greece? Turkey? Iran?
All I'm saying is beware there are rules and many countries that do take them seriously. the crews invariably are simply not aware (how many dozens of countries do they fly over/into?). Fly Olympic into Greece- how do you know the cabin crew won't finger you after arrival?