Earlier in the discussion, some had mentioned that it was made illegal for religious reasons... What are they? I guess I can maybe see some of the more conservative religions which already make drinking, music, etc. a sin as thinking that weed would pollute the body, which should be held as a temple for the soul...
I think that would be the major reason why the right would be against it; socially "conservatives" (though I disagree with the term, but I digress) would want any drug made illegal. It was a reason why some on the right are for banning cigarettes in public places, suing the tobacco industries, etc. And also for some of the laws in Utah regarding alcohol.
However I think that the further to the right on the political spectrum you move, you'd actually find more that would be in favor of it. Libertarians would agree more with the idea that the legality of drugs is a matter of individual freedoms. People should be free to make there own choices in life as long as it doesn't infringe upon another's freedoms. Smoking weed doesn't affect anyone else aside from the person that smokes, so a person should be able to smoke if they so desire. I would agree with certain limits, such as driving while under the influence since accidents occurring because a person was high does indeed hurt another's freedom, but those limits should be held in check. And when it comes to limits imposed on marijuana, it should be based at the state and local levels, like most other laws like murder, rape, robbery, etc.
Most of the problems associated with marijuana are due in part because of the criminalized nature of it. Violence associated with its trafficking resembles the same problems experienced with alcohol during prohibition. Same with the high prices, etc. And I hate the insinuation that pot is a "gateway drug". If that's the case, then so is tobacco and alcohol. The legal drugs also alter a person's perception of reality (being giddy on nicotine or loopy on alcohol) and can also being people in contact with the criminal aspects when kids try to acquire them when underage. So that gateway argument holds no water.