What got me started was the smell of pipe tobaccos and what kept me going was the variety of flavors, the craftsmanship of pipemaking, and the history behind it, with an emphasis on Britwood, particularly Barling. I also enjoy prep and packing, the codger scoop, lighting up, fiddling with the pipe during a smoke, as well as cleaning and maintenance. However, were it not for the flavors, none of the rest of it would long hold my attention.
The "smoke down to a fine white ash" is one of the more destructive myths surrounding pipe smoking. Most tobaccos will smoke down to a mottled gray ash. The last one that I can remember smoking that did actually reduce to a fine white ash was Sobranie made Balkan Sobranie Original Smoking Mixture, and that hasn't been made in 40+ years. Aside from that, trying to burn every last thread of ribbon will generate enough heat to damage your pipe over time, causing cracks and fissures in the wood at and around the base of the chamber. It's a really stupid metric for success.
Ultimately for me, it's all about the flavors.