iOS didn't always expose device orientation events in javascript browser. In particular, one of the first apps I wrote, for iPhone 3GS, specifically could not be a browser app for this reason.
Objective C is a hell of a programming language to learn just to access motion sensors.
And for anything else devices do that could have been done in a browser..
Nothing like that sinking feeling in the pit of your stomach when you realize you have yet another memory leak, zombie object or mysterious exception in the main run loop to debug!
Objective C is a hell of a programming language to learn just to access motion sensors.