I don't want to speak for anyone else, but I don't think that
@Buzz Rules was implying that it should be some hard and fast law; of course there is a set of Americans who may not ever need one as they don't travel.
What I was agreeing with was the general principle that most folks should get their kids passports. Who knows when they might need it? It can also teach them about what it means to have American citizenship and what the purpose of a passport actually is. That is how I introduced it to my son and it led to a great learning discussion.
Furthermore, It introduces kids to the concept of international travel - why we do it; what we can learn from it; how can we do it ethically and not harm the destinations we are visiting; helping them cultivate an interest in the world around them and be curious. This curiosity leads to understanding and an interest in other cultures and hopefully to breaking down barriers that overall makes this world a nicer place to live. You can call me all new agey or whatever but I truly believe that travel can change peoples lives and thus improve the world. And frankly, even if he never uses it, for those lessons alone, it was worth the 150$.
Just my take on the matter.