Any communications-auditing regime relies on detecting and preventing steganography. This can be immediate successful, but is an endless escalation that should cause honest people (ie those who aren't trying to restrict communication) to focus on node security.
While an IDS can indeed benefit end users, its same functionality can be implemented as edge software - either on the nodes, or if worried about nodes being already compromised, then a separate "network processor" domain. The only point of needing a centralized IDS is the centralization - top-down control.
If that was your intent (to start a political argument), then so be it, but if instead of picking a fight you would like to understand the problem space better there are plenty of smart folks on HN and elsewhere who can provide use cases and data ... to say nothing of vendors who will argue from either side depending on what they are selling.
hth, adric
Information architectures can't help but being simultaneously technical and political. The original "End to End principle" came out of utterly technical concerns. But codified into a principle, it becomes "political". This is inevitable, because the drawbacks of poor engineering aren't felt immediately, and in fact can be quite beneficial in the short term.
There are of course plenty of vendors selling top-down "security". Right in this paper, they say "the market for such DPI devices is expected to grow to over $2B by 2018". Power tends to centralize until it collapses, which is why we as individuals must work to rebuke such trends.
Closing your eyes and pretending the politics don't exist dosen't make them go away.
The old field of electronic payments is littered with papers detailing "secure" systems, but who's only novel contribution was a way of defeating security. They all went nowhere because to any organization that had the power to force adoption of such a scheme, preventing any encryption still offered the best value proposition.