Hiya, saving this question as I don't have time to write a full answer (as is lately the case, sadly), but you might be interested in two answers of mine that I wrote previously and in which I do address why and if opium was a menace and who used it - in U.S and England for the most part. Sweden is extremely interesting when it comes to alcohol use (it's where the term "alcoholism" was coined) and drug use as well, but I am not as well versed in it as I am with the Anglo-American situation. Hope it helps a little!
Here is one about the effect opium had on the society in England