One of my pet peeves is that nicotine has gotten a bad reputation for no other reason than media hype of cigarettes are bad therefor nicotine is bad. They ignore the fact that a cigarette is "doped" to the max with other chemicals to "enhance" it, that nicotine, without all those "enhancers" has some therapeutic uses and that nicotine is probably no more addictive than caffeine without all those "enhancers".
Flavors are a whole other question that needs a lot of extensive, and expensive, study though.