I don't really have an opinion on the legal age, but I think upbringing has something to do with it as well. My parents don't drink, and none of my siblings have really gotten into it. I've never really enjoyed it, I can't get my head around how other people rave about it. To me it's a waste of money and time(not saying this should be everyone's opinion, just that my head seems to be in a very different place to most people I know around my age).
I chose not to go to uni, and instead I work full time hours and have done since the year after I finished school, I would much rather be working than out partying and getting drunk. It's just not my scene. Instead, I have worked very hard to save as much money as I possibly can because I can see all around me that life = debt, and I figured that if I can work now while I have relatively little expenses, I can put myself a lot further infront later. So far it has worked, I have a nice car that I paid for myself and I have just taken on a mortgage. To me owning a house was one of my most important goals. I wouldn't be able to even think about owning a house for a very long time had I gone to uni and wasted all my money on alcohol and clothes and makeup, those things do not interest me in the least.
I wish people who go out drinking several nights a week could see a total of the money they spend on alcohol each year, I just can't justify the cost for no gain. If I spend a lot of money I want it to be something worthwhile that will benefit me, or get me closer to realising my goals(going to uni would fit into the 'worthwhile' category, I just don't think uni is right for me).