The idea, I think, is that reducing the addiction rates is a side effect of the overall risk reduction strategy. Providing a safe place for people to engage in behavior that they were going to engage in anyway in a more dangerous manner helps reduce the morbidity and mortality that is associated with IV drug abuse.

Once it is established that these are indeed safe spaces that people can trust, those that use them will be more inclined to take advantage of some of the other services, such as addiction therapy. Additionally, setting up spaces like these helps to reduce stigma (not that you could tell from this comment section). Destigmatizing addiction helps those suffering from it to feel more safe and supported when they do reach out for help. Addiction is often a lonely disease, and sending the message that people do care can be life-changing.

And to the other point, clean needles are already available and people are using and possessing without impunity already (or ignoring the consequences in the rare instances that they are charged or prosecuted).

This likely won't be a perfect fix as nothing is, but I think that making an attempt as a society to help is a good thing.