Personally I think the legal drinking age should be 18. I started drinking when I was 18, but didn't learn to do so responsibly until I was doing it in public. A bartender can refuse to serve, or call you a cab. Not that they always will, but I think it is advantageous to have at least one adult around keeping an eye on things. Sure there are plenty of irresponsible bartenders, but my experience says it's better than nothing.