“Convenient option” is probably just a bit the wrong word choice; a writer could easily sell “walking action scene” as a more “convenient” choice for a more action oriented movie, or sell Babs-As-Oracle and Cass-As-Batgirl as a smart decision for an ensemble film.
Name recognition is still probably Babs’s greatest advantage on a conceptual level - and Cass’s radical different by being so action oriented makes this more than the usual “which legacy character should matter more” debate.