They may be helkpful, but requiring one for a day trip for a family will cost Americans hundreds of dollars, maybe even in the thousands for an extended family as well as the months it takes to get one. Same for Canadians. It will kill cross border tourism and it won't be worth the cost to make short trips into each other's countries. It would be better tomake entering all of North America more difficult.
That's why passports should be required to go to any country outside of the US and vice versa.