It's the nicotine for me. It has to be, or else people (including myself) would find it no problem switching to smoking lobelia or one of the other aromatic but non-nicotine smokable herbs... if just smoking to be making smoke was the key.
I don't find the nicotine feeling even remotely similar between cigars, dip, cigarettes or the pipe. It seems even weird to compare them.
Think about this... when the first pipes and tobacco was brought to Europe from the Americas, the tobacco was 100x's as potent in nicotine as it is today. There were no Virginias, or even light Connecticut leaf. It was all variations of Rustica. And, there had to be some sort of hitch to make this novel new thing to do catch on. Some of the earliest reports on smoking in the Americas stated that it was a psychoactive effect, some reported relaxation, some reported clarity of thought, some reported some pretty wild things that we wouldn't take serious at all.
But, nowadays with almost no nicotine aromatics, low nic Virginias and other mild cultivars, and our experiences with direct lung hit cigarettes, dip, etc, we can't seem to find a consensus.
I propose that it is whatever you want it to be. I'll smoke for my nicotine relaxation, and you guys can smoke for breathing meditation, packing rituals, and whatever aspect brings you joy.