It's always been an edgy topic.
Alot of people don't think marijuana is bad for you, but others disagree. I for one, will arrest people if they do have the substance, but for me it is equal to smoking a cigarette.
Because there are so many different types of way marijuana can be grown and how it differs in different people's bodies, you can never just rule out that the substance does this to you, because sometimes it won't do it to other people.
I would prefer it is not legalized until we have more of a understanding towards it, but that is the what the majority of the states want. I know here in Minnesota a law that was coming to legalize marijuana was veoted about 23% actually wanting it.
As I said, it's always an edgy topic, because there are no confirmed papers about it in different areas, whilst in Colorado it may have been a huge thing with tons of papers coming out showing the effects of the drug (good vs bad) to get the victorious vote.