This may be a stupid question but is the language in some way tailored to game programming? Apple's examples at WWDC were game companies, their coding demo was a game, and this is the first project I've seen written in it - and it's a game.
Additionally, they're a quick route between code and something visual. If the demo yesterday had been "look how easy I can make a tableview", no one would have cared much, but the circus scene had motion, lights, and barely any code. People love spectacle.
That reads a lot more sarcastic than it should have, but it's unfortunately true. Swift was announced in front of a room of people who needed to be convinced to start migrating from something they all know (ObjC) in favor of something new, so you have to win them over quick.
