i thought i posted in here earlier, but must not have hit reply..
i think that changing the drinking age is a double edged sword. without a change in the culture surrounding alcohol, i don't think you can safely lower the drinking age. however, you'll never be able to change that culture without lowering the drinking age.
unfortunately, in the short term, lowering the age would be an absolute disaster. there would be a sudden influx of "kids" binge drinking and there would be a lot of negative repercussions. (and regardless of how you are legally defined, at age 18 you are still a kid. you really don't become an "adult"" until probably closer to 25.) however, i think over the course of 10 or 20 years, we would hopefully start to adapt an attitude closer to that that you see in Europe with a much more responsible attitude towards alcohol.