"Finally it's a shame no mobiles support WebGL yet. iOS actually supports WebGL, but they've disabled it! I'm not sure why they've done this, because enabling WebGL is crucial to high performance HTML5 games on mobiles."
The cynic says: App store! App store! Money money money!
Could be good reasons. Perhaps Apple's webGL implementation actually could be used for exploits, and until it's secure they won't allow it for general use. Notice the one place Apple does allow WebGL is iAds, which are reviewed & controlled by Apple.
And the cynic is an knee-jerk idiot. The App Store is not Apple's money maker by a large margin, selling iPhones is.
Also Apple HAS added WebGL support to iOS, only hasn't enabled it yet. Tons of reasons exist: battery issues, the implementation not being ironed out yet, and the security risk of WebGL.
Apple cares about the experience of using an iPhone, and if WebGL games on mobile safari suck the batter dry, stall or even crash, they aint gonna enable it just for to add one for mark on the iPhone spec sheet.
The cynic says: App store! App store! Money money money!