One contributing factor could be social stigma. The soccer moms of the world were brought up to "say No to drugs" where cannabis was one of those drugs. You can pry their glass of wine out of their cold, dead hands but I've personally seen them very nervous about a low dose edible. Perhaps some time and federal legalization will change that.
The current breeding techniques have produced varieties that are not conducive to the socialization (i.e. sativa vs indica). After legalization the market will need to have the marketing for sativas/socialization strains that will drive the development of happy/euphoric/uplifiting strains that do not promote sleep.
I suspect it's that alcohol and socialization go well together, while cannabis doesn't so it's better to enjoy it at home than at a bar.