I'm not sure I'm a large proponent of dropping the drinking age, most people show they can't handle alcohol responsibly even at 21, much less at a younger age. Perhaps if we adopt most of Europe's practice of introducing it at a younger age to where it isn't suddenly new and interesting at a later age.
You can't draft a bill that fits everyone, but it is always better to err on the side of caution, especially with peoples' tendency to do things in excess.