I don't know that we can't measure brain chemicals accurately. I am not sure what that might do for us if or when we do. Ultimately what needs to be changed is our behaviour.
If addiction is a learning disorder, it is far from simple. I don't think the term trivializes my experience in the least. I see it as a maladative behaviour that was reinforced through altered brain chemistry by consumption of a substance for which a tolerance is developed through repeated and continuous consumption.
I forget all the time that I used to be an alcoholic. It isn't part of who I am now. On the other hand, I never forget that I never drink.