Why is marijuana illegal for medical and recreational usage?

Considering that there is a recently released article in "Neurology" that states that smoked marijuana caused significant relief in pain caused by Peripheral Neuropathy associated with AIDS/HIV...also another article stated that smoking marijuana causes pre-mature aging of lung cells meaning that they die off before the lung cells can become cancerous. I know that these are all medical situations but if you are a cigarette smoker wouldn't smoking pot prevent lung cancer...all things considered why is pot illegal for any and all uses?Why is marijuana illegal for medical and recreational usage?
I can't answer why any drugs would be illegal. I thought this was the land of personal freedoms.
NIXON
Despite the many PC advise and the drop in it's legal status, this is bad stuff....honest. Long term studies show a significant increase in both low grade and serious mental disease in chronic users. I have certainly seen significant numbers of patients who have developed depression and more worrying schizo affective disorders. There is some scanning evidence of physical brain damage and brain shrinkage.
Also don't let anyone tell you it is not addictive! I have dozens of youngsters who just can't get off it.
Because anyone can produce it and the government wouldn't be able to tax it. If the government can't get their share, then they make it illegal.
because its a natural and cheap pain killer that doctors don't want to endorse. people that say its bad for you have never tried. it is offered to some patients for pain releif (i.e. cancer patients and those with extended pain like leg joints removed and replaced incorrectly)