Perfect. The card is a convenience for people who live near the border and travel frequently over it. The card is smaller and less expensive than a traditional passport. Inside the US, one needs no travel documents unless you're operating a motor vehicle.

Passports are superior to state IDs such as driver's licenses (or dependent military IDs) in that they are proof of citizenship. Unlike a birth certificate or certificate of naturalization it also combines proof of citizenship with photo ID. I don't think its essential for people living in the US but it is very powerful and if you don't use it for travel frequently, you can leave it in your bug out kit and rely on having ID if you lose or have to leave your wallet or checkbook.