A very good question. My answer would be that alcoholism or some other drug addictions are illnesses. I reach this conclusion through first hand experience of drug addicts. As these people get deeper into their addiction, it slowly overcomes them, they become their addiction - it defines their personality. I don't believe we can simply attribute this to a personality defect. Perhaps the better question to ask would be "do we do enough to prevent such addictions as alcoholism?" or "is enough done to help alcoholics?". The answer to both of these questions is a resounding "NO!".
Perhaps the main reason for today's record levels of alcoholism is the way in which alcohol seems to have pervaded all parts of society and how the booze culture is so prevalent. Accepting and conforming to cultural norms is the reason why a lot people start to drink in the first place and that's not just with alcohol. Personally, I don't drink and have never drunk alcohol, primarily because I am a muslim. However, my religion is not the reason for my sobriety - I simply have no desire to drink. Very few people (so I'm told), initially drink alcohol for the taste, more people drink just because it makes them less inhibited and most people (at least those that I know) drink simply to get drunk! None of that appeals to me and it seems that my religion previously acted as an immunisation of sorts to the social pressure to drink, until I realised that I simply didn't want to. I'm not sure I believe that any significant portion of the population could be genetically predisposed to alcohol addiction (or any other addiction for that matter), perhaps those who suggest that this is possible could cite some evidence.