I don't think "The Diamond Age" is a realistic prediction of the future. Quantum security systems can't protect anyone from intrusive governments which are already monitoring our phone calls, e-mails, and everything else. The US government even made it illegal at one point in the 90s to use encryption methods they couldn't crack. If necessary they'll make it illegal to own or use any computer that doesn't contain circuitry that allows them to monitor all activity, while still allowing quantum cryptographic systems that bar others outside the government from monitoring our activities.
Its not a question of privacy or ethics, but merely whatever gives any particular government a competitive edge at any given time. For example, the US has been studiously monitoring communications networks in Europe since WWII using everything from submarines tapping into underwater phone lines to monitoring cellphone towers. During the cold war this was considered a competitive advantage for the Europeans as well as the US, but with the cold war over now Europe has become a leader in the commercial applications of quantum cryptography. In particular their banks which like the US banks make a killing off routinely committing fraud and, in some cases, providing shelters and money laundering services for illegal drug cartels or whatever.
Whether a security system involves cryptography, a floor safe, or your own private army it always comes down to what you can afford, what you absolutely need, and whether or not it is advantageous for the government or whoever really runs the country.