There are issues that come into play way before physical dependence. For instance, some people are quite intolerant to opioids and exhibit severe nausea, chills and vomiting.

I broke my leg in a fight a few years back and found it much more tolerable to sit (and sleep) very still than to take codeine. I would have loved to have some sort of cannabinoid derivative available, and failing that, I might have considered smoking some cannabis.