First, I think it's an infringement on my freedom and pursuit of happiness to make drugs illegal. That's just me though.
Secondly, I think making alcohol and nicotine illegal is a step in the wrong direction and could hurt a lot. For example, at a university in california there is very promising research going on with tobacco plants. They are developing a treatment for lymphoma. If you make the tobacco (which unfortunately contains nicotine) illegal, then we have to look at the fact that we might miss out on some good that could come from that. People might choose to kill themselves slowly with cigarettes, but people with lymphoma generally don't choose that. It'd be sad to tell some people they had to die because we want to prevent other people from choosing to die.
The only thing I have to add to that is:
industrial hemp.
Oh wait...there's all that other medical research with medical marajawanna too.... 's