Clear thinker that he is, Brendon gets things straight: he argues that exterior appearance can be used in fiction to depict interior disposition, but he carefully distinguishes between appearance, disposition, and action. Brendon defends the fantasist's right to use apperance as a symbol of interior disposition, but warns us against equating physical beauty with interior goodness, which he describes as a category error.
More muddled on the subject is Michael O'Brien, who writes in A Landscape With Dragons:
Generally...it is true that the exterior forms that many traditional authors give to the morally or spiritually ugly characters tend to be ugly forms. Likewise, beautiful forms tend to express a beautiful interior life. This is a literary device that works well to reinforce the child's budding awareness of interior ugliness and beauty....
We have lost our sense of the holiness of beauty. By the same token, when exterior beauty is in harmony with a character's interior beauty, then the sign of the value of the tale or the character is greatly enhanced. Similarly, when worship of God is done poorly, it is not necessarily invalid if the intention of the worshiper is sincere. But when it is done well, it is a greater sign of the coming glory when all things will be restored in Christ....
Clearly, God is better glorified by a humble hunchback mumbling badly phrased prayers in a ditch than by a proud aesthete singing hymns perfectly, solely as an art form.... But what if the beautiful heart of that hunchback were to dwell in the developed art of the aesthete? Would not a greater glory be rendered to God by the restoration to harmony of both substance and form? [pp. 35-36, emphasis in original]
What Brendon says, correctly, is that goodness is beautiful and can by represented in literature by physically beautiful characters. What Michael O'Brien says, accidentally (I hope!), is that beautiful people are intrinsically better than homely people and capable of greater worship. Poor, poor, confused man. And did you note his use of the word necessarily in the third sentence of the second paragraph? Fumbling worship is not necessarily invalid if it is sincere, he says. It might just squeak by.
While I'm at it, I must quote O'Brien one more time because it's so much fun to watch him contradict himself. Observe his essay, "The Problem with Harry Potter," in which he writes, "In a consistent display of authorial overkill Rowling depicts...'bad' characters as ugly in appearance." Now compare that to the first paragraph quoted above, in which he praises "traditional authors" (whoever they are) for depicting evil characters as ugly.
In the dark and ugly landscape in which Michael O'Brien dwells, it is good and right to depict good characters as beautiful and bad characters as ugly--unless of course J. K. Rowling does it, for in Michael O'Brien's dark landscape, Rowling can't do anything right. Chesterton once complained that in the minds of some non-Christians, any stick is good enough to beat Christianity with. And in the minds of some of today's Christians, any stick is good enough to beat Harry Potter with.
Finally, as for the rights and permissions of fantasists, the solution to this and similar dilemmas is simple. To the Christian writer of fairy tales, fantasy, and sf, no other command do I give you than this: "Love God, and do as you please."