The idea that she might have designed Regina’s ward-drobe is interesting. Most likely it’s just symbolic of her taking over from Regina.
Making her Cruella though would make her the anti-Elphaba, it amazes me people didn’t pick up on that. Even if she wasn’t based off the Wicked version it would be very jarring to have a version of the WWW that was polar obvious(exploiting/killing animals rather than liberating them). What if instead, if they were adapting Wicked, Madame Morrible was Cruella? She could be the designer of both their wardrobes and some other relation to both of them.
They might end up having a story arc similar to Animal Farm from Fables(though I sot of hate Fables).
Also, another source reporting her as Elphaba –
I don't cause commotions, I am one.