One argument is that yes, it should because it may reduce traffic fatalities between the ages of 18 and 20. According to the Canada Safety Council, the highest rates of impaired driving in Canada are among younger drivers.
In 2002, drivers aged 19 to 24 represented 56 per cent of reported incidents; a stunning 44 percent of fatally injured drivers aged 20-25 had been drinking.
Commenters on the CBC's article were overwhelmingly against the idea of increasing the age, and many made good arguments for it. For example, youth even now find a way to get alcohol if they are not the legal age; and just raising the age is not as helpful as more education about the hazards of binge drinking; and also, there was the idea of raising the driving age instead.
It's certainly true that it's too easy for underage drinkers to get their hands on booze. There are many many willing adults who are more than happy to buy it for minors - a mischievous favor perhaps, or the adult see it as a way to look good in someone's else's eyes. There could underlie a problem with how society in general deals with personal circumstances.
Taking a closer look at the psychology of behaviour, the why of behaviour, would be a good angle to approach alcohol or any substance abuse. What is it about the way our society works that makes alcohol and drug abuse an enticing activity?
Often times, over-drinking is an escape and/or a painkiller. A self-diagnosed treatment for some pain, frustration, personal unhappiness, an escape from reality. Alcoholic drinks are associated with good times. It is seen as a reward, a celebratory staple for parties and occasions. And, some times, getting drunk may be accidental, a bit too much appreciation for a fine tasting libation. It is glorified in society by consumers and brewers, and promoted with the "good times" association. The problem is that consumption gets out of control and is associated with a generous helping of bad times.
Education about alcohol and substance abuse is a good approach to tackle the problems of binge drinking, and drinking and driving. As well, it would be helpful to first understand why young people, and adults, drink to excess, and why intoxicating substances are sought after in the first place. No doubt, reasons will vary, but one reason at least could be because of some void in one's life. What are the voids in peoples' lives? Why do they exist, and how can voids be filled in positive ways?
Raising the drinking age from 19 to 21 won't hurt the situation, it might help, but is far from finding and fixing root causes for binge drinking and alcohol abuse. A serious comprehensive attempt to reduce alcohol abuse requires a larger step than just raising the legal drinking age. Consulting psychological and sociological studies on what factors are involved in drinking behaviour is a start. Let's see what they have to say, and what they might suggest.