I've seen plenty of people go nuts for want of a cigarette with or without alcohol. The problem, IMHO, is not free booze, it's the smoking ban combined with the general stress of being SLF which causes air rage. Throw in a few free G&Ts and the problem gets worse but free booze does not, I think, cause air rage on it's own.
It would be really interesting to know how many non-smokers have been done for air rage incidents - coz I betcha the vast majority are smokers. It's the lack of nicotine that drives 'em nuts, the booze just exacerbates the problem by diminishing their inhibitions about complaining about the lack of smoking.
Allow a limited number of smoking seats on a limited number of flights and I guarantee the number of air rage incidents would plummet.