I disagree. Although there will always be some divergence, age is generally a good way to determine maturity.
I don't think the drinking age promotes alcohol abuse by many of the youth of the United States. I would argue that popular culture produces this current, but there is no point in blaming it completely since our actions speak louder than words (or images on the television screen). My point: it would not do any good to change the drinking age, because we've been steeped in vulgar values that are continually being promoted by our friends and media. The majority of youth believe that one should drink to get drunk. They have not been taught about drinking alcohol in moderation--a glass of wine at dinner or a beer at the saturday market. More simply, people hate change. This is one of those changes, such as vernacular liturgy, which most people (minus the youth) would dislike, since it has been the norm for quite a long time. Therefore, we probably will not see the drinking age change anytime soon.
But since we're beating a dead horse, a meme is in order: