I'm not in journalism, so if anyone is, please correct me if I'm wrong - but everyone (regardless if it's MSN, NBC, CNN, whoever) wants to have the "big story" of the moment for a few reasons: they want to build credibility (as being "THE source for breaking news", which of course equals more viewers which leads to other benefits for them.
(remember when Anna Nicole/Britney's shaved head was on every channel and newspaper?)
They aren't gonna say, "Oh, well, we're CNN, and NBC already has this story because the package was sent to them, so let's post pictures or something else instead."
My point is, they are there to inform us (among other things) which is what their doing. Granted, the news coverage is a bit much - but I think it's because it's such a huge story that has touched so many people.
I definitely agree that it is a lot because like someone else already said "it might make some other nutjob want to go out and top it".
Anyway, just wanted to throw that out there.