I like the way Mike explained it. It's true, in my experience and belief--the disease does not "excuse" what happens under the influence, and forgiveness is something we do for ourselves, not for the person who has wronged us.
The one thing unique to addiction, of course, is that the brain changes interfere with the sufferer's ability to see the effect the addiction is having over him/her and his/her life and loved ones. Everything is skewed. That's where interventions do come into play in a useful way. If many people force you to consider something you cannot see for yourself, you may finally have to accept the possibility they are seeing a truth that you cannot.
I do believe alcoholism is a disease, an illness, a disorder or whatever. I don't believe people choose to become addicts or alcoholics. But some people are more willing than others to accept reality and the need to address the problem.