What would you have said in the 30s? 50s?
Was the atomic bomb a waste of money? (Heisenberg about single-handedly convinced the Nazis it was, and he should be canonized for that).
Was the space program a waste of money?
Airplanes?
Telephones?
Every new tech, every new system has always had someone saying exactly that. "Its a waste of money, it'll never work, why bother".
And giving up because a solitary bomb might be carried in, well, that's true enough. Are you going to talk the RN into stopping patrolling their bases, cause, after all, someone could walk up to the base, and detonate one, so it would be pointless?
So *in that case*, its pointless. But since, by definition, you don't know what case is about to come up.. be prepared for as much as you can.
Maybe intercepting ballistic missiles is almost impossible with other projectiles. (I don't think it is, but we'll see).
BTW, the RN *has* an excellent anti-missile system. (Seawolf?). The write ups on it I've seen all said to the effect of ~"If this were made and sold by the US, it would be standard equipment for every Western country".
Which leads me to believe that its not an impossible thing to do. And being prepared for one eventuality is a good thing.
Addison