After reading all the responses here, I am left wondering when the last time someone here who thingks the non-smoking rules at hotels are stupid/meant to be ignored, don't apply to them etc light up a cigarette on an airplane? If they haven't anytime recently why not? Clearly the law prohibiting smoking is an illegal one and anyone who chose to fight it in court would score a major victory for those who can't go 3.5 hours without smoking.
I'm always courteous enough to step out on the wing when I want a smoke in the air. It the closest thing to a balcony on the plane.