Would you prefer, your children to go to a black market dealer, not knowing who the dealer is, if the dealer is going to try and sell harder drugs to your child, they won't don't know the quality of the marijuana purchased, and or if chemicals have been used in growing or what it has been sprayed with plus the chance of being busted and ending in a Thai prison.? Or in any country with draconian drug laws.
Or
Marijuana is controlled by the government, so they can tax it and make money instead of the big dealers profiting. Now it is being tested to medical grade cannabis, there is no threat of being busted or getting a possible criminal record or having to mix with the underworld to get supplies.
Opportunity to be a leading country for research for medical marijuana uses, education, with potential huge industries.
Having marijuana illegal doesn't stop people using it if they want to. To some it makes it more exciting.