Something that is illegal, is by definition a social taboo. The removal of that taboo implies more acceptance. The fact that more people use it will only increase acceptance by word of mouth etc. and that's at minimum.
The only question is by how much will usage increase?
Already, with severe legal restrictions and controls, opioid use is rapidly increasing the US, which is what we call 'extreme product market fit' (i.e. the drugs 'fits' our dopamine pathways) see [1]
The other major factors are 1) addiction / tolerance and 2) self-medication 3) money, i.e. capitalism.
As for 1)
"Roughly 21 to 29 percent of patients prescribed Opioids for chronic pain misuse them"
"An estimated 4 to 6 percent who misuse prescription Opioids transition to heroin." [2]
Those are just simple, top line numbers, and very potent at that.
Even with limited marketing and 'soft non-acceptance / promotion' - I believe it's something that vast numbers of people will seek it out 'just to party' or for 'the Vegas' trip etc. and especially for 2) i.e. as an easy painkiller/mood moderator which will leave a lot of people addicted.
As for 3)
If it's legal and profits can be made, they will be made. Investors at large may be 'moral' but there is always plenty of 'highly amoral' capital to do whatever, and in this case, it'd be producing the product with the most 'product market fit' in existence.
Increased use of opiods etc. will have no upside, only downside. It has to be regulated and controlled, it's best to keep it at a minimum.
In Canada they prescribe them by the pill, not the 1/2 bottle, i.e. you get a single pill for toot surgery because its just so addictive.
[1] https://en.wikipedia.org/wiki/Opioid_epidemic_in_the_United_...
[2] https://www.drugabuse.gov/drug-topics/opioids/opioid-overdos...