Cigarettes != tobacco. Tobacco is an ingredient in cigarettes, and not the only one, not by a long shot. Literally dozens of additives are included in cigarettes, many of which are designed to make them more addictive.

Secondly, modern tobacco absolutely was "made" the way it is, first through selective breeding and then genetic modification to (among other things) increase Nicotine content. Much in the same way that modern weed is far stronger than the stuff grown 50 years ago, so too is tobacco.