I have known some addicts (most now dead), and FWIW I think all addicts should have access to drugs like methadone that don't give a high, but can help control the addiction and help the individual to function. I agree drug addiction should be treated as an illness.
I think there should be much less waiting time between an addict asking for legal medication and them getting it. As far as I know (things might have changed) it can take months to get a prescription. Too much can happen during that time as the first visit to the doctors may have been a real crisis point. Having to wait months for medication is not on - fancy having to wait months for painkillers or antibiotics if you have a bad infection.
As I said, addiction should be treated as an illness. Even if the individual never comes off drugs totally, they can use legal medication to normalise things in the long term, and so live a better, more mainstream life - like holding down a job, having a proper home, living with their families, not on the street.
I base this on the knowledge of one of my friends of many years and her partner. They are both heroine addicts (or ex addicts as they now take methadone or similar AFAIK- obviously I do not know their exact habits as it is none of my business - they may well be clean by now, though I know they still have counselling).
They both hold down jobs in the caring profession, are good parents to their child, and have a stable, loving home life. It is not a perfect situation but without access to free medication and counselling, I do not know where they would be now . I know that when my friend first went to the doctor, she did so very reluctantly, as she felt the whole process was so long drawn out and complicated.
I also very much agree with winnie's post that prevention is the best cure of all.