you have to think big business, paper companies, dupont, logging companies, so on & so forth would be destroyed by the legalization.
By that I mean hemp, hemp seed oil(dupont will hurt), hemp paper products(newspaper comp. are heavily invested in land with trees on it as well as companies that make paper plates, bowls, etc).
Its not that they dont want to, they'll(meaning our congr-ass-men and woman wont get their pockets lined by these companies any more.The country will move forward by leaps and bounds but they wont.
actually, interesting you mentioned dupont.. when dupont made nylon, there was a HUUUUUUUUUGE push to make industrial hemp illegal. i think for one of the world wars they had to allow it again to make canvas or something then back to being illegal so nylon could make its stand and the rich could line the pockets of the richer..