i think its because with an analog you always got the same volume of smoke - regardless of brand.
With
vaping its so variable that if you dont see the big plume of vapour, you feel like you didnt get the hit you so rightly deserve. For example, as the battery goes down or the juice starts to run low, the vapour is less, and you get a weaker hit. So, simply by association - you end up connecting vapour production to satisfaction overall.
Its a working hypothesis, but its the best i can do.