The premise with Star Trek's future, is that humanity does not need artificial stimulus to be happy and enjoy themselves. I am not saying Marujuana is good or bad, or that it needs to be viewed as one or the other. My point was if they are going to tackle drugs as an issue, to show it being used safely to enhance the crewman's time on board the ship, but also show how it can become a problem as someone becomes dependant on it.Are we going to evolve past having stress and needing to relax? There's nothing wrong with weed, we just have a society that doesn't accept it because of propaganda. Studies have shown it to be fairly beneficial. The only downside is that in certain places you can be arrested for having it.
The only reason it's a Schedule 1 drug, which means the US government thinks it's more dangerous than cocaine and has no medical benefits, is because it gave them an excuse to arrest hippies and African Americans. So what's more likely to evolve past, a puritanical attitude about a harmless plant or our desire to unwind after work?
It would be betraying the ideals of the show, or the progress of humanity as it is portrayed, to suggest drug taking is a positive, or something to aspire to. In the same way that alcohol was replaced with something less harmful (Synthahol).