If you and your DH already have passports, consider the following three possibilities. 1. Assume that if there is a crisis at home, and your children don't have passports, only you or your husband will be able to fly home on an urgent basis from another country -- and the other adult can remain with your children.
2. Assume that your children won't fall ill in another country and have to return to the U.S. on an urgent basis, requiring a passport for one or more children.
3. Assume that if there were a crisis of some sort, you would prefer to travel with your whole family.
Only you can pick the best alternative for your family.