Earlier quoted context omitted.
A buddy who is an excellent reverse engineer assures me that this isn't a conspiracy. Crypto services had to be verified by a key; the NSA's crypto services were classified, so they couldn't let Microsoft sign them; therefore, they needed their own key. The key is only used to authenticate crypto services, which I think Douglas Adams would describe as Mostly Harmless. I don't have the reverse engineering skills/IDA P…
Answers from my POV: 1 - Privileged access to the dominant consumer operating system, also used by many corporations likely to be targeted. 2 - Minimal effort cost. Good will cost seems like something NSA ignores. Exposure to risk seems minimal given the existence of NDA contracts. 3 - I think anyone who isn't deluded and/or a member of the "nothing to hide; nothing to fear" camp already knows you can't trust Windows…
It is worth it for the NSA to backdoor crypto because, if the implementation is solid and the keys can't be stolen, then no matter how many resources they pour into cracking it the math will remain inflexible.
There is no computer in the world with that kind of security. If it is smartly configured, they'll use 0day. If its airgapped, they'll compromise a sysadmin's computer and wait for them to connect to it (think Stuxnet.) If that isn't feasible, they'll walk into the data center and put malicious hardware into a PCI slot.
If we persist in thinking of the NSA as a boogeyman logging every packet and backdooring every OS, rather than discussing their real capabilities and motivations - what they are, what they should be - we will become paralyzed to act against them, they will continue to operate without meaningful oversight, and our rights to privacy and to secure software will languish.