It is the 'intolerance modification effect' of marijuana that people for whom politics is a business find dangerous: when you make your bones by fragmenting and separating people based on particularized intolerance along dimensions of gender, sexual orientation, skin color, ethnicity, religion, culture, wealth, education, class, and on and on, you really don't want them smoking some herb that not only makes them tolerant of others, i.e., mellow, but an herb whose use makes a laughing stock and irrelevant of those who make their living from intolerance and the control thereof for profit and personal gain... 
Politicians in general who cater to lobbyists who do not want things like marijuana legalized. It's up to the people, to replace all these idiots in positions of power! 