They are by no means the most harmful drugs. Belladona would be a good choice if that was what you were considering.
Tobacco and nicotine are two of the most attractive of the moderately harmful drugs. Most people aren't really attracted to strychnine.
What happened is there is a puritanical groups that seized control, and they decided that they had the right to tell everyone what they should be like, and that what they should be like is the way god made them. There are advantages to this as well as disadvantages, so they were able to suppress all except the very most popular drugs. Their success can be measured by the fact that the DEA will prosecute doctors who prescribe too much pain relieving medication. The underlying belief is that if god causes you to feel pain, you should be in pain.
In most cases I believe that drugs should be legal to purchase, and to sell, and to manufacture, and to transport, but not to advertise either directly or through sponsorship of media that use "placement ads" for them. And in this I include pharmaceuticals used to treat illnesses as well as other drugs, and I feel no distinction should be made. (I.e., I don't feel any of them except antibiotics and, perhaps, a very few others should have their sale regulated.)