Beauty, [Briony] had discovered, occupied a narrow band. Ugliness, on the other hand, had infinite variation. A universe reduced to what was said in it was tidiness indeed, almost to the point of nullity, and to compensate, every utterance was delivered at the extremity of some feeling or other, in the service of which the exclamation mark was indispensable.-Atonement by Ian McEwan
Literacy is more than just reading. It is writing. It is forming a comprehension of character and an ability to articulate thoughts and attributes. As a long time writer, I have work with the spectrum of ugliness in many of my characters. As I stated in my previous post, I am a strong believer in character flaws and ugliness- both inner and outer- is a powerful flaw. My best example would probably be Elphaba from Wicked. Yes, I'm bringing up Wicked again; there is a reason it's my favorite books. Elphaba- known eventually as the Wicked Witch of the West- is consistently described as a monstrosity and by all means visually unappealing. However, it is more than just the Ugly Duckling hideous-on-the-outside-beautiful-on-the-inside factor that I'm interested in. There are several times throughout the book where Elphaba is an extremely amoral character or even immoral at times. It is that playing with the line of morality that I find truly interesting in a character.
So what does any of that have to do with ugliness? Such moral conflict leads to ugly action and, in my opinion, a very interesting story. Don't get me wrong, I love a moral character too and given the right author said character can work out just as well. I guess what I'm getting at is the ugliness is flaws. It can be concealed or outweighed, but it is still there and that is exactly why people get invested in characters.