Having recently started down he pipe path at (nearly) 50, I've asked myself this question. I enjoy tobacco and have smoked cigarettes and cigars. Still love a good cigar but cigarettes are nasty and I hope to never pick up that habit again. My dad was a pipe smoker for many years so I suppose that has something to do with at least opening the door of interest and curiosity. Since I've been smoking for a few months now I can confidently say that I enjoy the flavor and smell; I enjoy the peace that it brings; I enjoy combining it with a good beverage, be it coffee, beer, or whiskey. I guess I just love smoke in general: campfire, smoked meats, etc.
Also, I am something of a collector and have a tendency to "want it all" when it comes to a new interest. I see how this naturally applies to pipe smoking. I am absorbing all I can about pipe brands and shapes, styles of tobacco, etc., and, well...I want it all.
My obsessions typically wane over time, but I think this one will be around for a good long while.
As for nicotine, I've never seen myself as a nicotine fiend. With cigarettes it was mostly a social thing, and I've stopped and started several times. I enjoy a good cigar. I enjoy a good tobacco pipe. That's it.
Cheers!