I think if you want it Leagilized or Decriminalized you will need to start somewhere.
The American public has been fed bullshit for almost 100 years. if you leagize it then the pushers will target second graders. they used all kinds of scare tactics. So a harsh punishment will need to be offered in order to squash public fears about MJ and minors. Just like they have for Alcohol.
Once the public is past the baby in the crib hitting the hooka then the laws can be adjusted.