So, even if someone else, even the NSA, has access to the public keys on the server, whether it's Apple's server or anyone else's, they still could not decrypt the message I send, or a message sent to me. What's all the uproar about?
The entire idea about public key cryptography is that the public key can be publicly shared without compromising secrecy - and the public nature of the public key is key (no pun intended) to the entire scheme.
You are, probably intentionally, conflating two different types of privacy. My privacy (modesty) inside my house is not the same as expecting privacy when I spew something out over the World Wide Web.
It's all a matter of what you consider your security boundary to be. There are many legal opinions on this, of course. (e.g., If you leave your blinds open, is it fair game for your neighbor (or police) to peep inside your house using binoculars when not on your property? If you're using grow-lamps in your basement to grow some "private" crop, is it OK for the gendarmes to search for your grow-lamps from a helicopter via infared signature - and then act on that information?) Reasonable questions; no really simple answers...
Your privacy on the Internet is generally not well-respected, and if you really want to control information exchanged that way, you're probably best-off using self-signed certs and a mechanism that supports them.