The name change could have been part of the plan all along... Consider... a "Starling" might grow up to be a "Star"... so the city "grows up" after the last couple of years of mess... maybe they were planning this from the beginning like they seem to have planned other elements.
At the ComicCon interview, producers said they will address the fact within the season's storyline that they can't/won't have a third storyline about Starling City getting blown up. I imagine the city name change ties in to that. In a "let's move past our tragedies and start with a new beginning and new name".