Are there any good reasons NOT to legalize cannabis anymore?

http://www.huffingtonpost.com/2009/08/04/the-benefits-to-legalizin_n_246356.html

As Glenn Beck says in the video, this is ridiculous. Why should such an innocuous drug, and such an incredibly useful and environmentally friendly fiber, be spawning violence, wasting government money, and actually harming the environment? It's completely stupid, and it was never smart in the first place. (1937: "uh, something called marijuana... I think it's a narcotic or something... yes the AMA is behind us [except they weren't]")

Legalize the stuff already.