If you're going to create a new character, then 1) that new character will take up considerable amount of space from the other GA superheroes without a codename to draw people to the comic or 2) it's Gay Token Man! making a cameo every now and then. So DC did what they did because of Alan's familiar codename, while Alan Scott himself was deemed expendable for this experiment because he hasn't been a sales draw for a very long time.