I favor weed, more specifically, I think you should be able to buy land and use all of it to grow it, and sell it, and maybe let the state gov't put a tax on it.
That being said, it isn't something I think is my god given right.
When a substance is capable of impairing you, and you have a society where pretty much everyone has a 2000 pound plus hunk of metal and plastic on wheels that goes as fast as you want then society has a big interest in saying what goes and what does not go.
Substances that impair you enable you to get into your car and kill my family. Society has an interest.
Back in the horse and buggy age you could walk into a pharmacy and buy heroin. Modern technology changes things.