Kunis originally came up in that broadcast for Luthien, and Corey remarked that he liked her better for Aredhel. She has a "darker" look about her (Corey's word) that he really liked. He didn't really elaborate more than that, to my memory.

I don't really have an opinion of her either way. But she was mentioned in the session, so I thought I'd include her in the discussion.
Mila Kunis looks really good in elaborate dresses, so I imagine if we did cast her as someone, she'd be fun to dress. A character who has a 'courtly' presence might work better than Aredhel, though, who may very well clean up nicely but prefers life outside of court.