What happens if one day, meta-data collection ceases forever and lives are at risk? On that day, some may look back and say the wrong decisions were made to end meta-data collection. Now consider that such collection continues on as it is believed to be the best insurance against national tragedy. Years go by, a tremendous treasury of memories of every action of each individual and group exists. Nothing. Calamities both large and small still occur. Why? Tools of investigation and protection are most potent when they are either unknown or unassailable. Meta-data collection is both known and assailable.
Those intending actual harm know what to avoid. As well, misinformation greatly degrades the effectiveness of such tools. Actual people are more effective in such instances. More globally, scenario planning is far more useful. What are the actual tools of destruction? Pondering that means seeking genuine safeguards in the form of regulation and oversight that will mitigate much that a mere accounting of activity would be hard pressed to address.
Trains can be derailed and cause destruction. Well, plan for that and maybe put in appropriate preventative suggestion to industry to abort such attempts. Chemical release that incapacitate. Where would such chemicals come from anyway? Supply chains are manageable. Power grid damage. What are the feasible ways that can happen anyway? Such access points can be governed for greater safety. They can be improved in ways that do not require a default position of suspicion.
One day, we may look back and see how much we could have done things differently. That day could be today. A day in which we returned to a presumption of innocence. That sentiment may be unrealistic in some ways, idealistic even. It is nonetheless, one of the many ideals near the center of the social contract writ large.