I don't think it's debatable (or at least, not debate-worthy) that nicotine alters brain chemistry in a way that perpetuates dependence on it. I think the main difference between the effects of nicotine on the brain and some of the other activities you mentioned, with the possible exception of chocolate consumption, is that those activities don't involve a substance that is not normally produced by the human body. Nicotine has the striking property of altering dopamine receptors so they (in layman's terms - I don't pretend to know the precise process) become skewed toward recognizing and accepting nicotine molecules, and less receptive to other substances that would otherwise have been able to bond to them. (I sometimes liken the action of nicotine molecules in the brain to Al Haig's famous "I'm in charge here" line immediately following the assassination attempt on Ronald Reagan). Thus, I disagree with your assessment that religion (for example) and nicotine are equally addictive. Religion doesn't introduce a foreign substance into the body; it, and most of the other activities you mentioned, just prompts the body to produce substances that the body is capable of producing by itself.
I don't think that it's necessarily "silly" to closely examine what nicotine by itself does to the human body, but I think I've been clear that vaping is infinitely preferable to smoking. I'm just not sure I'm 100% comfortable with being dependent on a substance that does have profound effects on the body. I think these effects include increased heart rate and blood pressure and increased adrenaline levels, and those effects don't strike me as trivial.
I think we'll see a lot more good research in the near future about the effects of nicotine alone, without any of the conflation of the added effects of cigarette smoke. The presence of MAOIs in tobacco smoke is extremely interesting, since it seems to me to be true that they significantly increase the addictiveness of nicotine. Maybe that's for another thread.
I'll conclude by agreeing with you that it's very nice to be able to tweak one's brain chemistry; it's just that the brain is very complex, and I think great caution should be exercised when mucking around with it.
Cheers.
Nicotine Molecule