Interestingly there have been some research reports out talking about at least 3 of the yet unstudied chemicals (that are now being studied) all in the "nero" family (I believe) that in combination with nicotine and in the presence of or because of combustion have some sort of interaction that makes them addictors too. From what I read, alone none of these would be addictive but in combination and the other factors they are.
The research was talking about why, all things being relative, a smoker will fail to be able to stop smoking while just someone addicted to nicotine will be able to kick the addiction. This was all rat studies again where they had the rats that they had given nicotine to until they were addicted, and had the smoking rats that lead to this because they could taper off the nicotine addicted rats and get them to stop craving, or eventually even wanting nicotine but the smoking rats preferred smoking to just nicotine even if the nicotine was easier to get, and that when they were tapered off nicotine they never got where they would not go right back to the smoke.
Anyway, apparently these three chemicals have been found that do this and they now suspect there are more, which pretty much hold up what your saying. I mean we all know there's more to smoking then just a nicotine fix, its mostly been directed to the psychological before (oral fixations etc). If there are, once these studies are complete) then nicotine replacement as the nicotine is now is not all that needs to be replace. The other thing that lead to this study was the percent of people that use nicotine replacement and still smoke, don't end up with nicotine poisoning from higher levels than they are used to and do it because the nicotine "is not enough".
What I got out of reading the paper was that there is nicotine addiction (just pure nicotine) and addiction to this "changed" nicotine. So maybe the 'changed' nicotine a different level of cravings/addictive force/withdraw effects then just pure nicotine.
It will be interesting to see where it goes and if true how long ago the tobacco companies knew...