Well….. hmmm….idk if I trust them but hmmmm. I guess Arthur is our seasons villain, apart from Emma. This half I mean. I wonder if she atleast exists in Once canon. Just cause we wont see her doesn’t mean she still isn’t black fairy
They said it was because they already had so many Camelot characters already. I’m guessing another reason is that they have Emma as the Dark Swan, so we pretty much already have a witch. Not to mention Zelena is still around. Morgan being included could have been redundant.