Meth should NOT be legalized. I can see cocaine and heroin, but meth poses significant harm to those other than the user. Those idiots who cook meth in clandestine labs risk blowing their surroundings to smithereens, so meth is a public safety hazard. Legalizing meth only leads to more potential harm to not only the user but his or her neighbors. Good people should not be subjected to that kind of risk.
It's not legalized, though. It's decriminalized, which means people caught in possession of small amounts of the drug will no longer be thrown in jail and branded a criminal. Dealing and manufacturing is still criminalized.
All I know is, I've seen too many friends affected by drug addiction and I come from an area that was beaten pretty bad by it. Jail/prison does not help. It only makes their life a hell of a lot more difficult, which in turn pushes them deeper into drugs in many cases. What they need is proper treatment. Addiction is simply not a criminal justice issue, and the system is not equipped to handle it.