Don't know if this helps but when we raise questions about security where i work a rather well know theme park near the village of Alton and these meetings are with senior management it appears its down to global iconic status ?
To comeback to your main point why,let's go with terrorism and that the plane is somewhere on the ground with the 'innocent' passengers/crew in a secure area. I would imagine hi-jacking/stealing with Europe/Australia/Israel/New Zealand let alone USA/Russia/China is all most impossible ? It now...
I would not go quite that far,however from what we hear and see in the media America is just a small player in the background offering some support nothing in my opinion could be further from the truth. We know that there are no Americans on board so for them that takes out the human interest...
Take a look at this,makes you wonder however assuming the plane was on auto pilot would it have not just flown on towards China ?http://www.dailymail.co.uk/news/article-409703/Ghost-flight-horror-crash-blamed-pilots.html