It is mostly based on taxes. It is legal to make wine or beer in the home but if you distill alcohol , even 1 gallon, you go to jail for tax evasion.
I would like to see pot legalized for one reason, hemp. Hemp is a wonderful plant with hundreds of uses in manufacturing and was widely grown here in colonial days for rope, paper, cattle feed, etc. It isn't grown now because it takes too many resources to separate the hemp plants from the pot plants and so licensing for growing hemp is extremely difficult and so nobody grows it. Instead we import it from other countries. Hemp can be used for bio-fuels, textiles, and more and grows faster and uses less nutrients from the soil.