I'm a hypnotherapist and would say that in my experience the psychological addiction is far more powerful than the physical one. I never use the words quit/quitting, giving up, packing it in etc when helping people. People at a subconscious level reject those terms - because we don't like to give up or quit on anything.
Its about becoming smoke free and breathing normally - amongst other things - including getting to the bottom of why the individual smokes and dealing with that issue - e.g. if its a coping strategy for dealing with stress. You weren't born a smoker.
Letting go of the smoking habit is really difficult and it takes a lot of strength. I certainly don't underestimate the difficulties that people experience but its my personal belief that e-cigs and vaping don't really help in the long term.
I took Hypnotherapy, it worked, for a while, but I started again. Some of it stayed with me, it just didn't quite get to the bottom of it.
Whatever it is that made smoking such a part of my identity, is now satisfied by the (maybe) much less damaging, and cheaper E cig.
After being on it for such a length of time, the habits and rituals that surrounded tobacco are now starting to diminish, almost gone altogether. I doubt I'd go back on tobacco if the ecig wasn't there.
It was more or less those habits and rituals that kept me smoking. As life moved on, I didn't want to smoke anymore, but the practise was so engrained in me, I couldn't stop.
I'd tend to agree with you that it's the mental urge to smoke that is difficult to overcome, the addiction to nicotine, at least for me, is very minor, or non existent. I certainly don't get any where near the withdrawal symptoms from the ecig as I did from tobacco. I can go all day without the ecig if I have to, and feel little different. I couldn't do that with tobacco.
I know the ecig is not addressing the base issues that led me to smoke, but I'd say most those issues are overcome now anyway. Having said that, I am aware that part of the reason I use it, is to address issues that could be better overcome by altering my thinking processes.