It is engrained in the BBC public that they watch news at teatime, if ITV had a bulletin at 8pm everyone would just watch the Six and then not want to watch a bulletin two hours later.
Everyone? The whole country? No point in ITV doing news at all then?
Surely if ITV is 2nd place in news, moving a main news programme to a slot that doesn't compete with the other side is the best chance you can give yourself to make an in-road.
Eventually, one of the main ITV news programmes will fade away - I say it's best for the remaining programme to be in a prime slot that assists the remaining schedule and doesn't clash with the Beeb.