Rest of the world no strict rules.
Family rather than government.
Kids won't be so curious because they have access to it.
Decrease unsafe drinking activity. Starting at a young age, young adult will not be provoked to drink and drive when they get the license.

Lower the risk of breaking the law to get a drink.
The teenagers will drink no matter what the law is.
Drinking is an enjoyable activity. Eliminating the age to drink will decrease the alcohol induced injuries.
Eliminating the drinking age reflects unique demographic
Good for economy.