I always thought the reason was so that, because News 24 and World now had the same onscreen graphics, they needed to fill the space on World where the clock was on News 24.
I think that might be a chicken or the egg switcheroo - the design of the DOG
using the News Channel's clock area for the extended World News name was more likely a clever design answer to the problem of compatible graphics. Very unlikely the name change was informed by the design of the on-screen graphics. Especially when that only lasted a few years before being replaced by a completely modular system.
And yes, they should have stayed with News 24. And the Australian Broadcasting Corporation shouldn't have copied them a couple of years later, and renamed our ABC News 24 to the ABC News Channel as well.