I think the real trick in all this mess isn't in what the government wants states to do with their drinking age... it wouldn't really matter at all what the legal age was if parents would sit down with their kids and simply be frank with them about alcohol.
As a child I grew up in a house with an alcoholic father. I love the man to death. He is my hero in many ways... if you make a joke about one of those ways being his drunkenness, I will break you in half. Anyhow, he and my mother were always really plain with me about drinking. My dad told me a lot of stories about the trouble he got into drinking, the dumb things he did, and mainly a lot of the problems it has caused him later in life (most of those health problems). My mother, on the other hand, drinks maybe one cocktail per month. She was a pillar of responsibility to me so far as alcohol was concerned, and I learned from her that you didn't need booze in your life in order to enjoy it.
Both of them sat down with me before I went to college (I was scared of alcohol when I lived at home because I saw how my father reacted to it) and they told me that I was a grown man, and could make my own choices... but that I'd have to live with those choices. If I wanted to drink, that was fine, but any trouble I got into drinking I'd have to deal with on my own and live with any repercussions resulting from it. They instilled alcoholic esponsibility in me before I made the choice to drink, and I think that has made all the difference today.
Just some food for thought.