I can see how you can think I'm being disingenuous on point three, let me expand a bit. I'm not glad he got busted for cheating on his wife just because. My point is that the military uses propaganda, spread through the mainstream media, to further it's agenda (which I think is bad). Petraeus' image as a straight shooting, old school, unimpeachable hero type was used as a cover for the morally unsavory aspects of our recent wars. It just happens that he was brought down by a very human indiscretion which was revealed through the use of an insecure network.
It illustrates that the indiscriminate sharing of information on public networks gives increased transparency into the lives of people, including the rich and powerful. Even if they know how to cover their tracks, they can be exposed through the insecure practices of "civilians" with whom they interact.
Something that Assange doesn't quite address in the excerpt is that not only do people not care about about secure communications, they actually want their personal information on the "public" web. Most people do not have a group of people they would like to communicate with but in a highly secure manner. The exception would be for affairs.
Even people working for companies that have requirements for secrecy need low friction method of exchange of information with larger networks of individuals that they don't know well.
There are negative consequence to this (specifically the ease with which the govt can spy on its citizens, as Assange points out).
But the cost to individuals, and to society, is too high for whatever benefits a widely used "darknet" would have. The value of the internet is connecting large numbers of people who are engaged in the various life activities that people do. It is not compatible with secure networks. The porousness is a feature not a bug.
I mean really, what sort of activities would an average person find it useful to use a secure network for? Illicit, illegal, or insurgent. Not a real high demand for this.
FWIW, I think what Assange has done with Wikileaks is heroic. I just think his vision of a sort of private internet is impossible. It would have to be based on "insiders" and "outsiders," a sort of division in the population. Those sorts of division are only maintained through nasty applications of "real life" power as far as I can see.