[arethuza]

I'd have thought in this context "newsworthiness" is perhaps more related to whether it is possible to craft an eye catching headline from a story.

[TeMPOraL]

It is, precisely for the reason GP gave. The eye-catching headlines are usually ones that tell you something that's unexpected. Sometimes because the event is unexpected, other times because the headline is massaged until the point it sounds as if the event is something unexpected.