While it does seem unfair to deny an 18-year-old the right to drink at the same time they are allowed to join the military or vote in an election, there are strong arguments against it as well. Most of them are heady and backed by statistics about drunken driving and binge drinking.
My reason for supporting the drinking age at 21 is more selfish. I work in and frequent bars, and I don’t want a bunch of drunken infants ruining my night at work or on the town.
People in their early 20s are bad enough without allowing teenagers to invade the bar scene, too.
Leave the drinking age alone and focus on more important legislation.