A majority Americans (almost 60%) now favor legalization of marijuana legalization; younger Americans even more so. A recent Pew study shows a big change in public opinion from only 10 years ago - the positions pro and con have basically flipped.
I don't smoke (anything) myself, and I tend to be more in the "if you are not hurting anyone else, go ahead and do what you want" school of thought - oddly enough, I have become more like that as I get older.
I do get the impression though, and I may be wrong here, that some folk who are for legalization perhaps think that they can then show up to work and smoke a joint at the lunch break. I fear that might be frowned up as much as swigging from a bottle of vodka in the lunch room.
I am not entirely clear myself if workplace drug policies are primarily because the drugs themselves are illegal, or if the concern is more about impairment and job performance, or a bit of both.
If we do take a stroll down the legalization road, there will need to be a lot of adjustments made all around, in all areas of society. Is marijuana a gateway drug, does it really rot your brain, what are the long term health effects compared to cigarettes?
It's hard to even know the answers to these questions, as both sides are so strongly opinionated - so we may need to judge the results in hindsight - not always the best vantage point.