> While it's easy to start believing this is the only motive

No one said that. Files leaked by Snowden describe NSA's activities as durable, even against legal attack, thanks to layers upon layers of digital, procedural, legal, and other forms of defense in depth. Among them, plausible deniability and dual use technologies. You have pointed toward both. So their tactics worked on you.

> But yes, there is no doubt that what you mention is a major motivator for at least some of the people pushing for it.

Don't forget that ubiquitous surveillance is exactly the tool most useful for blackmailing or discrediting opponents as well.