Well, I can shed some light on the exact reason for cigarettes being allowed. I used to work at a certain company. They paid hundreds of millions in taxes. They were in constant threat of litigation. All the companies making cigarettes got together and started talking about literally closing every single office in the US and moving to Europe. They were going to relocate to a country that would give them legal protection and in exchange they would generate a like amount of tax revenue for that country. They were seriously considering doing it........... one year later, they settle with most of the Attor Gen's. Even though there is still some stuff going on with lawsuits, it erased a huge portion of the problem surpressing their stock, namely the uncertainty.
Bottom line, there are a lot of powerful people in the country that either benefit from the taxes that booze and cigs generate, or they don't mind a late night snifter, or maybe a good Cuban.
If there were a bunch of meathead Senator's, we'd be set.