Crime is at a low relative to a spectacular peak of crime so high that it challenged the safety of privileged rich white people in major cities. It remains a scourge of the underprivileged.
It's not just that I think "eavesdropping should be done by domestic agencies", but also that I think eavesdropping should be done under the aegis it has always supposedly been done under, one that acknowledges that eavesdropping is the most intrusive investigatory act the government can engage in, that monitors the private thoughts of individuals and in many cases causes defendants to effectively testify against themselves.
It would be difficult for a domestic law enforcement agency to build anything resembling the infrastructure NSA has built, for exactly that reason: the cost/benefit ratio just couldn't ever work out. That's why NSA/FBI "fusion" is so scary to me; it repurposes an infrastructure that has a workable cost/benefit because it's budgeted for in a military context. That's what I mean by incentive problems.
But once again: "parallel construction" isn't new. It's also what happens when highly-placed criminal informants help make cases against organized criminals; to use the CI themselves as part of the chain of evidence would be to risk losing that CI. I'm not sure how much the practice bothers me in this context. And, like I said: other parts of the "parallel construction" story bother me a lot more than the NSA evidence; for instance, our new unelected canine prosecutors.