The point of building nukes isn’t really to launch a nuke at someone, it’s to make others decide that attacking you is too risky. Missile defense isn’t perfect, so even if it probably would stop them, there’s still a risk one gets through, that someone would have to take into consideration before launching an attack. It’s even more a threat against Isreal, since they have less time to intercept, and even one missile getting through would destroy a comparatively larger fraction of the country, being that it’s fairly small.
The point of building nukes isn’t really to launch a nuke at someone, it’s to make others decide that attacking you is too risky. Missile defense isn’t perfect, so even if it probably would stop them, there’s still a risk one gets through, that someone would have to take into consideration before launching an attack. It’s even more a threat against Isreal, since they have less time to intercept, and even one missile getting through would destroy a comparatively larger fraction of the country, being that it’s fairly small.