Why is smoking marijuana against the Word of Wisdom?

Why would it be considered against the Word of Wisdom? Marijuana is not addictive. Marijuana is not harmful to your body in any way. It is publicly perceived as being bad for you because it is illegal but if you actually research the studies that have been done on Marijuana you will find out that it is actually a medicine out there helping many people. If it weren't for the amount of money it would take from different industries it would be legal and helping out many more people.

Also the Word of Wisdom is not a commandment. Read up on D&C 89 and search it out for yourself through study and prayer.