The daughters are probably considered 'ugly' due to Korean Standards, but not from other country's standards. Koreans but a much higher emphasis on certain characteristics of 'beauty' (small nose, large eyes, youthful, thin, ect).
The older step sister is very pretty from my PoV, and the younger step sister is down right adorable.
I'm curious to see how this progresses and if Ashley holds a grudge or if they manage to repair and build a mother-daughter relationship (and if she still ends up with the prince. How funny would it be if she found love elsewhere and one of the step sisters and the prince fell in love instead?)