Let me say that I think we largely agree, and that I'm deeply sympathetic to your immune system analogy. The US over-reacted, badly, and many, many innocent people were killed because of that. And arguably we are all less safe now, precisely because of that over-reaction.
I have been extremely critical of that reaction in the past, along much of the same lines you state. I haven't changed my mind on that, but I have also come to realise that it's actually really hard to calibrate risk in this situation - in the case of car accidents or lightning strikes, say, we can forecast expected outcomes very accurately, and the variance of those outcomes is relatively low. The threat model for an intelligent opponent is very different - history is a poor guide and the variance of potential outcomes is very high.
I have been extremely critical of that reaction in the past, along much of the same lines you state. I haven't changed my mind on that, but I have also come to realise that it's actually really hard to calibrate risk in this situation - in the case of car accidents or lightning strikes, say, we can forecast expected outcomes very accurately, and the variance of those outcomes is relatively low. The threat model for an intelligent opponent is very different - history is a poor guide and the variance of potential outcomes is very high.