Deadline states that the decision comes amid chatter that Warner Bros is reevaluating DC Universe in light of the upcoming WarnerMedia streaming service. It is suggestive, but the article does not draw definitive conclusions like your post above.
Apparently Crystal Reed, the actress who plays Abby, wanted to do the white hair, but the producers said no. I have a feeling they were saving Arcane for the second season. In show, she's an orphan who was raised by the Sunderlands, but there was some shadowy figure that haunted her nightmares when her mother was still alive, who I assume will be revealed to be Arcane.