I read several times the words "responsible, intelligent" I think you fail to realize that many on boarding become neither of the above!
If you have ever flown on a foreign carrier you would quickly find that one pax puffing away on an e-cig will incite a veritable wave of the real thing being lit up...
As annoying and potentially scary as intoxicated pax are, I have not in my years of flying, ever seen one combust and start a major fire... At the end of the day, smoking is much more immediately dangerous to a safe flight than someone who's had a few too many sherbets...