Wow, uglyboring Viv? Have you...really paid attention to her design? At all? Her clothes, her headdress...boring isn't a word I'd describe for Vivienne. She's not my type, but she is lovely.
Cass wasn't "redesigned to be ugly." Those are largely the same features as she had in DA2, just with a new engine. 
I don't think it's possible to have a rational debate about tastes, really. Yeah, I've paid attention. I dislike her looks and she doesn't look interesting as a character (romance aside). I don't say that she is badly designed altogether, that would be a way too subjective assertion, but she does look uglyboring to me.
As for Cass, it's not just another engine - she has a different model, not just imported to a new engine with increased polygon count, but with dozens of small and not so small changes here and there which go far beyond cosmetics, thus she does look very different. That can be, of course, said about any old character with a new model, but in her case those changes totally broke the character for me, she simply looks too different and the charm she had in da2 is gone.