1. Being curt with someone can lead to them going home and beating their spouse to vent their frustrations. Should we then never be curt because it might lead to domestic abuse? How improbable does the outcome need to be before this kind of argument is considered invalid?
2. Dragnet surveillance alone cannot lead to actionable intelligence, it can only be used to confirm other sources of intelligence. The false positive rate is simply too high. Would they still drop that bomb without that surveillance? In most cases, probably.
3. Weapons have only one purpose: to physically harm. Surveillance can have many legitimate purposes. They simply aren't directly comparable.