On the day of the Sandy Hook massacre, a Chinese man entered a public school, in China, and stabbed 22 people, ranging from elderly women to children. This received little coverage mostly because of the shocking events that transpired at Sandy Hook, similar to the lack of coverage in Iraq due to the Boston Marathon. By your logic, the reason as to why this event was seldom covered (and, if it were, awfully vaguely) is because the event does not constitue a...newsworthy value?
That is my logic, exactly.
It may be newsworthy in China, but honestly, what happens in rural China is not of much interest to me. And the New York Times probably does not sell very well in rural China. Sandy Hook was much closer to "home" and therefore of much more interest to me.
It is not the job of the Western media to give every happening in the world the same coverage. If 22 people in a Melbourne school had been stabbed the same day as the attack in China do you really think the Australian newspapers should have given equal coverage to the Chinese event? Of course not. That is not how Australians would rate the importance of the events.
The media, like any other commodity, tries to provide the public what it will buy. And these days you can buy just about anything. And like the remote control for your TV, you can block what you don't want. It is a long way better than state controlled media. Which, in theory, would be the only way to guarantee equal coverage of everything in the world. Except, in practice, it is perfectly obvious that a state controlled media is a lot more biased than a free media.