What other reason could it be? That it's a boring story? That it's pre-determined to end in love & peace? What?
What you and all of us are seeing in action is a phenomenon that is very familiar to non-Americans that watch American newsbroadcasting. Its instructive, actually, and please understand I mean nothing untoward by this comment, I just thought I'd point it out.
What we have are two big stories. I won't begin to try and determine which is bigger in the end. We have a developing breaking story related to the sniper, but information will come in spurts. The other syory is a very fluid situation in Moscow (ie - not in the U.S.) that could go ballistic at any second and possibly result in the loss of hundreds of lives. The expectation would be to cover both and update changes in either situation as they occur. But that's not what's happening.
The networks will replay and rehash and reanalyze the sniper developments until they wring every bit of mileage out of it they can. The Moscow situation, on the other hand, might just as well be taking place on the dark side of the moon as far as they're concerned.
When you hear foreigners whine about American media being self-absorbed and disinterested in any story that doesn't directly affect Americans think of tonight. Not saying its justified (it is AMERICAN media, after all) you're seeing a perfect example of it and being placed on the short end if you want up to date continuous coverage.
Just another reason I love FR!