I for one don't even see why people WANT to drink. I mean, I sure as hell don't need to be boozed up to have fun, not to mention that there is absolutely ZERO benefit from it. It's expensive, it's unhealthy, and it makes you really, really stupid until you wake up the next morning puking your guts out while your head throbs like a thousand war drums. Sure, that doesn't happen to every one, and sure, drinking doesn't always mean getting drunk, but there's no threshold you pass where before that drinking is good for you and after it becomes bad. It's just different stages of bad for you, ALL THE TIME. Add that to the fact that alcohol tastes like shit no matter what form it's in and you have yourself an all around terrible social convention. Oh, right, "it's an acquired taste." Yea, well I'm sure if I ate shit for weeks on end it eventually wouldn't taste so awful either!!
*phew* But of course, that's just my opinion on drinking. And smoking too, I guess.
Anyway, age limits are there because kids are stupid. Kids meaning anyone from 1-25 pretty much, but 25 is pretty long to wait so we kind of settle for 18 and 21. I know I wouldn't trust my 14 year old self to vote, or drive, or really anything that would grant him any kind of responsibility beyond owning a dog.