There's also the matter of limited warfare and not being able to use nukes for every defensive purpose. A nukes-only approach to national security means that y

There's also the matter of limited warfare and not being able to use nukes for every defensive purpose. A nukes-only approach to national security means that you nuke over the slightest provocation, which will earn you short-term victory at the cost of international condemnation and likely intervention. No one likes a nuclear powder keg. For a practical example, let's say we never bothered to invest in point defense for our destroyers and they were completely vulnerable to Chinese anti-ship missiles. One day China sinks a destroyer as a show of force. Should we nuke Beijing? Or would it be better to have a strong Navy/Air force in place to respond conventionally by taking out the missile launchers?