You bring up a troubling point. Nobody really knows what really happened behind the curtains during the production of Born.
-In short, Lerche (Who did Seasons 1-3) wasn't available,
-The negativity around the end of BORN (Which the creative team actually went on the record and apologized for)
-Risa Taneda (Xenovia's Seiyu) not being available because of her medical hiatus.
-They changed the character designer so it's more along the lines of the Light Novel Illustrations now
Take your pick , any or all of these issues were a factor in that decision