It took a vengeful God to confound the languages of man the first time around. This time around we have gone into do it ourselves mode as everyone who wants to either segment markets, is too lazy to improve an existing language, or just wants a monument to their ego creates a new language.
Swift is little more than a potential attractive nuisance and it's hardly in Apple's (The great creator of attractive nuisances) to open source it. They want it to become as popular as possible without becoming universal. That way they will have the largest possible code base and developer base trapped in their system without easy ways to exit.