I'm of mixed opinion. I'm uneasy about the idea of status crimes. From a pragmatic perspective, I believe (though I haven't researched the statistics) that raising the age from 19 (as it was in many states) to 21 did, indeed, succeed in reducing drunk driving fatalities.
I think the problem is that our culture is not one in which we are taught to drink responsibly. Hence, when first given access to alcohol, the consumption is anything but responsible. By prohibiting such access until people are of an age where they are supposedly more responsible to begin with, such irresponsibility is minimized.
Not the best approach, but I don't see our culture changing teach more responsible behaviour anytime soon. On the contrary, I think we are still moving towards blaming others for our problems.
Of course, as one who doesn't drink, I may not have the best perspective on the topic.
Now on the related topic of the smoking age, I'm all in favor of the movement in California to raise the age to 21. Here my reasoning is very different: I don't think anyone should smoke, and setting a higher age should reduce the number of people who start smoking. This would be a move consistent with the trend to reduce smoking as a part of our culture. (California, like most western states, is large enough that the problem of people crossing the border to buy cigarettes is only an issue in a small portion of the state.)