Steven Den Beste responds to my question about anime. Thanks!
Generally, characters who are young, or beautiful, or sympathetic, are drawn with very generic facial features. Characters who are old, ugly, eccentric, or evil, are drawn with more distinctive facial features.
To me that immediately brings to mind Chihiro in comparison to Yu-Baaba in Spirited Away.
[McCloud's] theory was that when characters are drawn with minimal and generic facial features, then they are more accessible because we fill those characters with our own ideas of what they are. If characters are drawn with more specific details, then we do less of that, and as a result the character feels more different, more foreign. It's like being held at arm's length.
This is very helpful. I've been fascinated by how anime artists/cartoonists are able to capture certain things often which such simple art. As one example, I've always found Yuu in Samurai Champloo to be pretty. But she's pretty not because the artists drew every detail of her face, but because they were able to capture some essentials and leave the rest of the details out.
I do have to find my copy of Understanding Comics when I get back to Nashville.
Update: Steven has an update to his post that covers another thing I was thinking about:
I've long had a suspicion that one of the big reasons so many anime characters have unusual hair colors is that some character designers simply need more than are present in nature in order to differentiate the characters they're designing, due to the fact that they can't individualize them using the natural cues we actually rely on to recognize other humans.
That doesn't get done in every anime[, but it's] an extra degree of freedom to add along with differences in hair length and style, figure size, height, and presence of glasses.
There was a study done where they took groups of people who were similar, e.g. "young Japanese women", "middle aged white men" and took photographs of their faces. They did careful measurements of their facial features and used a computer program to create for each group a single picture of a face which was the average of all those in the group.
What was interesting is that when people were shown the resulting images, invariably they were thought of as being attractive.
All other things being equal, an underdrawn face will seem attractive to us because we fill in the details unconsciously with "average" values, and "average" faces are good looking. That's the fundamental reason why Yuu (your example) seems attractive to you.