For those that don't think it is that bad, would you consider leaving your newborn baby with a babysitter that you knew might smoke pot right after you leave for work or an appointment? Would you want your child's bus driver to have a joint before taking the kids to school? When you can't trust your own husband to be on top of things for your kids and give you time to work or go to the store without feeling wary, that creates tension and unneccessary worry for the other parent, even if he's a real nice guy.
It's great if it just makes you unambitious and lazy and relaxed, great, good for you. But, when it makes you a paranoid, flippant asshole that others have to live with you can't tell me that it's harmless to a family.
My friend's husband was speeding while they were driving home one night and he had a bag of weed in the car. The cops arrested him in front of his 4 year old daughter. She was very distressed about it. Nice. Too bad he had to be so careless about his "simple little harmless habit".
"When caught between two evils I generally pick the one I've never tried before." Mae West