Roddenberry was right in that in the future no one would smoke. Think about the changes in health between the years 1970 and 2010. In 1970 over 50% of adults smoke, now it is less than 20%. People who have money tend to eat better and drink less alcohol. I honestly believe that fewer and fewer people in future generations will take up smoking, just because of the expense and prohibitions thereof.
To begin, YES I realize how old this thread is, but that doesn't mean that it's not relevant, perhaps moreso today considering the changing attitudes towards cannabis as well as the terrible opioid addiction crisis we are facing, so it's worth thinking about the potential for use/abuse in the future.
So first off what strikes me about all the arguments against drug use/abuse existing in the distant future, the most salient point would be to simply look back at the entire history of the human race and understand that as long as we've existed humans have used drugs of some form or another. Whether cannabis, alcohol, opium, tobacco, cocaine, mushrooms, peyote, DMT (ayahuaska), jimson weed and the list goes on and on.
Strangely, part of the counter argument is that in the distant future, humans will be living such healthy lifestyles that they won't need to take drugs, and frankly that is the single most ignorant statement, bar none. And I mean it, it is ignorant in the extreme because it automatically assumes that people take drugs simply because there's something wrong with them, lol, seriously???
But OF COURSE that argument is true where addiction is concerned, but to then look at all other drug use and the users and paint them with the same ridiculous brush is missing the point completely, and that is that we do drugs, BECAUSE IT MAKES US FEEL GOOD, and can also have benefits that go beyond the obvious medicinal uses that you might think of. Psychedelics like peyote, mushrooms, LSD, DMT and others have long been known to have amazing beneficial affects (when used properly) and have been used in religious ceremonies as far back as we can find evidence for. There's a heck of a lot more history where drugs are concerned, and for most of the history of our species, drugs were generally accepted, often revered, and it is ONLY RECENTLY that society has created such a negative stigma towards their use (and yes, addiction is a massive problem and needs solutions/treatments, but criminalizing them IS NOT the solution as we can see from the war on drugs).
So when you take that history and combine it with the FACT that most drugs definitely make people feel good/better (in the proper doses sans addiction), HOW is it possible for anyone to REALISTICALLY imagine a future where this fact suddenly changes??? If anything, I believe there will be more and BETTER drugs, ones that still intoxicate and get us high but without the negative side effects. In fact I believe on possibility is that humans will eventually come up with neural implants that could reproduce the effects of most drugs but without needing to actually ingest them.
Or, as in the case of tobacco, I'm betting on humans genetically engineering them so that they still have all the characteristics that people enjoy, but without the carcinogens. BTW, people DO smoke cigarettes and cigars BECAUSE THEY ENJOY their flavor and the relaxing sensation, not simply because they are addicted. But if that route isn't possible, then the fallback is that, and of this I am absolutely certain, we will find a way to treat/cure ALL CANCER, and probably within the next 50 years (science/medicine is actually closing in on this now), and barring even that, the probability that we will be able to clone or 3D print any organ in the body will be a reality in the next 20-30 years tops.
So NO, the health question will not be an obstacle to the use of drugs in a future where technology has advanced to a level as is probable in the Star Trek universe, and those who don't understand this simply lack sufficient information and imagination to see this.
We're ALWAYS going to want to be able to kick back and relax after a long days work/play, and crack open a nice cold brew, or a snifter of single-malt scotch or a drag on some dank bud, that will ALWAYS be true until such a time as we no longer have organic bodies (but who knows, maybe as cyborgs or androids, we may never lose the desire to scramble our neural matrices, lol, it's just part of being human ;?)