Oh, Lord. I can just about imagine it.
Developers: Visual C++ 2017 throws 2,048 compiler errors when I try to compile a project that compiled cleanly in 2015.
Microsoft: Oh, yea. We deprecated all of the C++98/03'isms and we threw some warnings in the last compiler update. Can't complain about having to rewrite your code when it's not convenient if you didn't follow deprecation with impending effects warnings!
You are living in a fantasy land. The real world is different, and doesn't work that way.
It may be okay for you if you're developing apps for an iPhone that are rather small or the kind of B.S. I see in the Mac App Store (3MB apps for $20 or whatever)... But I don't think someone writing an app the size of i.e. WordPerfect or Microsoft Word in Swift would - at any rate - appreciate changes like this which break code.
Every update to the language has broken code to this point, and as the breakages get more and more complex Apple's shoddy developer tools (i.e. Xcode) are going to get less and less effective at reconciling those changes automatically (and Swift Codebases will grow larger as time passes, theoretically, as well) and it will become a real problem for a non-trivial amount of developers.
You're acting like they just broke someone's 200 LoC shell script. It's more serious than that.
Also, they're making it too risky to learn the language right now. Beginners shouldn't be learning on languages that are changing every 3 months - in fundamental ways, in some cases. Additionally, a beginner can barely find a book that is up to date on Swift at this point.
Fortunately, there is still Objective-C.