The e cig argument has been done to death here!
The reason they are not allowed is simple and you seem not to have grasped it. On a full aircraft managing the passengers is a bit of a dark art. Smoking is banned but some mis guided souls still do it in toilets etc.
How would people know that the chap in front puffing away on his e cig was not smoking the real thing and light up?
When anti smokers see the passenger with his e cig they call the cabin crew and demand they stop smoking.
Lots of people have no knowledge or understanding of e cigs and think they contain same ingredients as tobacco so don't want them near them.
So when they first became common and after many incidents on board the airlines took the sensible approach and banned them.
I never get the connection between smoking and the drinking of alcohol it's true a very small number of idiots get drunk and cause problems on aircraft but the majority enjoy their glass of wine or G&T and harm no one.