1. Why was this app created?
2. How expensive is it to run this app? (no seriously, even at scale, I can't see this getting more expensive than a few thousand $ a month - which at NBC's level should not be too much of an issue?)
^ more views, more money and probably more profits.
I don't see why editorial responsibilites couldn't be a little more decentralized to lower costs. Give a number of editors Breaking News-level access in their CMS and check a box when a story fits the criteria. But NBC isn't in it for the public good. The app probably simply didn't generate enough revenue to justify the costs.
You aren't accounting for staff time. All software is a living organism, they can't just lay off the developers and expect it to keep working.