Apple has tried to limit the use of cross-compiler technologies to allow developers a develop-once, deploy-all solution. They want Cocoa and Objective-C to be the platform for mobile computing.
Unfortunately developers usually go towards the path of least-resistance, and even though HTML5 is just another dog with the same fleas, it is becoming the platform of choice.
By adopting HTML5, it opens the market up for Android and, to a lesser extent, Windows Mobile. Not to mention any PC or Mac with an HTML5 web browser. Though those HTML5 features again vary depending on the browser and platform.
Did you know Google Chrome can run C++ apps natively inside the browser? Google Chrome is it’s own HTML5-based operating system.
Even with Metro, HTML5 is still treated as a proprietary Microsoft thing. If you want to ensure that your code is not “view-sourced”, your main alternative to straight HTML5 and JS is to work with a WinRT component.
The walls of the fortress just look a bit different in Redmond than they do in Cupertino.
I wonder if it was Microsoft Research that found HTML5 adoption might hurt Apple’s profits.