I know that research on tobacco is full of bad science and bad actors, and experts in different fields (such as social psychology) continued to publish bad science on the topic well into the 2000s. This includes your 2002 German paper (which I can’t read because of a paywall).

Your second source says nothing about addiction in the chapter you posted, however they do talk about addiction in chapter 6, and they claim that most people agree that smoking is addictive, but heavy smoking is more addictive.