The point is most people are dumb and think they are smart. These dumb people think that if they just change everything everyone's lives will be better. Making it hard for these dumb people to make sweeping changes to society without the support of a supermajority is a good thing.
We’re a big, diverse nation. The law should follow convention, not lead it. (Not for any high-minded reason. The War on Drugs is the law attempting to dictate convention. Simply put, it doesn’t work.)
