If nicotine were considered beneficial the reasearch commentry would have been worded differently. e.g.
"Nicotine isn't just addictive. It may also interfere with dozens of cellular interactions in the body, new Brown University research suggests."
could be
"Nicotine's beneficial effects on clarity of thought might be mediated
through its effect on dozens of cellular interactions in the body, new Brown University research suggests."
The wording of the article assumes that nicotine being an exogenous substance must be bad. Caffeine, high glucose foods, chocolate etc all exhibit the same "addictive" effects attributed to nicotine. There is one striking difference between nicotine "addiction" and most other addictions that is often not mentioned. The effect of nicotine seems to increase clarity of mind and thought. (many other drugs do the opposite). No nicotine "addict" has lost his job, wife and property due to progressively deteriorating mental condition etc. as is common with most other substances.
When reading the results of research we must bear in mind the reason for the research. Nicotine has been branded as an addiction and research into stopping people from smoking is mostly funded by pharmaceutical companies that could generate huge profits by treating people for an addiction that they do not have.