Please read up on diacetylmorphine maintenance programs. There is copious literature on this.
Laudanum was used safely for the better part of the late 19th century. The word "heroin" is actually a trademark of Bayer (yes, the same folks who also gave us "aspirin")[0]. It was sold successfully and without any large-scale devastating effects for several years; the reason it was eventually outlawed had nothing to do with any negative repercussions of the drug on a large scale.
As for methamphetamine, according to the MTF and NSDUH studies, the majority of people who have used methamphetamine in the last 30 days do not meet DSM criteria for substance dependence[1]. That's not looking at everyone who's ever used methamphetamine; that's looking at people who have used it within the last month. Clearly it can be used "without affecting all of society"[2].
This is, of course, ignoring the fact that methamphetamine is Schedule II and can be obtained legally (albeit in rare cases) with a prescription (under the brand name Desoxyn).
[0] Both trademarks are now generic; Bayer eventually lost these trademark protections. This is why your local drugstore is allowed to sell acetylsalicylic acid under the name "aspirin" (with a lowercase "a").
[1] Most also wouldn't meet the DSM criteria for substance abuse either, except for a technicality in the criteria that references the legal status of the drug, which is naturally self-fulfilling.
[2] Unless you are looking at the economic impacts (ie, Nicaragua 30 years ago, North Korea and Afghanistan today, in which case you have a point, but that only serves to emphasize the need to short-circuit these black markets with legal ones).