LOVEINT: A dozen or so individual employees misbehaved in a reporting periof of 6 or 8 years, were found out by their own admission or NSA internal reviews, and were punished, mostly or entirely by discharge or forced retirement. Not good, but also not enough to rubbish the entire agency, which probably employs several ten thousand or more analysts at any given time.
The Bluffdale, Utah data center is largely a lights out operation. At completion, the local newspapers reported that ongoing employment would be in the neighborhood of 200. The analysis is done elsewhere.
The three deep contact chaining limit probably represented a pragmatic compromise between missing significant intelligence and producing so many results that anything of significance was obscured by noise.
Those who start with a presumption that the true purpose of the government is to control the citizens and suppress dissent as much as possible might conclude that all government surveillance is illegitimate and should be ended. Those who think the government has a proper role in trying to anticipate what can go wrong and prepare to oppose it might conclude that things like surveillance cameras nearly everywhere and databased communication metadata have a proper place in supporting that role but require close supervision to prevent misuse. In the US, at least, the overwhelming majority of police power misuse has nothing to do with mass surveillance or targeted communication surveillance and much to do with inadequate training and tactical misjudgments by police officials, and self-promotion by prosecutors. Most of this occurs at the state or local level of government, where internal controls tend to be more lax and less uniform, but they occur at the federal level as well (e. g., Ruby Ridge, Branch Davidian, Aaron Swartz).
It strikes me as inconsistent that we seem to acquiesce in, or even demand, handing over to our government immense power to do good (provide medical care, ensure full labor employment, for example) and tend to oppose vehemently granting it powers arguably connected to ensuring public safety, which many would agree is a core government function. One might argue that the surveillance fails a reasonable cost-benefit analysis, but that differs from the usual argument made, that the surveillance, along with the capability to do it at all, is intrinsically illegitimate.