re: Why isn't weed legal?

Most good answers in this thread have already covered it, but by time my generation (people in their mid twenties-early thirties) come to be the ones passing laws it'll be legal everywhere. I also anticipate we will take a much different approach to drug laws and turn away from the heavy handed hard policing agenda, to something more like Switzerland where they have established rehab centers people can go to get get clean needles, a shower, maybe a meal, some counseling. That's how you combat addiction, not locking people away.