In The Atlantic, David Thier describes “How the ‘Harry Potter’ Movies Succeeded Where the Books Failed.” I haven’t seen all the movies or read all the books, so I can’t comment on their relative merit, but notice this in Thier’s post:
The basic story in Harry Potter is an old one, and a good one. The boy of destiny is plucked from ordinary circumstances and becomes incredulous when he’s told the truth behind his real identity. Some training, trials, and a crisis of self-confidence later, he emerges as the true hero ready to defeat ultimate evil.
In real life, it seems like the problem isn’t often defeating ultimate evil: it’s identifying ultimate evil. Or recognizing that ultimate evil doesn’t exist very often, and more often there are banal evils, or inadvertent evils, or people just trying to get along but harming others as they do, or working in favor of malign self-interest, or some variation on these themes. Adult literature tends to recognize this. Children’s literature seldom does. Even The Lord of the Rings spends a lot of time trying to decide how to respond and who should wield power. Harry Potter seldom does that, from what I can recall: Harry is destined from birth. I don’t appear destined from birth to do much of anything; neither does anyone else (more on that below).
Robin Hanson says something similar to the preceding paragraph in “Beware Morality Porn:”
[. . .] movies usually focus more on whether characters have the strength of will to do what is obviously right than on whether they have the wisdom to discern what is right. And movie characters rarely have to choose between the praise of associates and doing the right thing – key associates usually support doing the right thing.
He uses Lord of the Rings as an example, although I don’t think it’s as appropriate as some others. The book version of The Lord of the Rings makes a point of showing how Aragorn, Gandalf, and other “good” characters work to limit their own power and define what the “right” thing is, beyond the defeat of Sauron. In the past, the Elves and Númenóreans repeatedly treated with Sauron, to their detriment. It’s not completely obvious what the “right” thing to do is: in the “Council of Elrond” chapter in The Fellowship of the Ring, proposals about using the Ring against Sauron are debated. It’s true that, by the time we get to The Fellowship of the Ring, it’s pretty clear Sauron’s the bad guy, but only because of past book-time experiences with him.
As mentioned above, I think movies and books have a larger problem (and one that, if I recall correctly, Harry Potter does address to some extent): virtually no one is “destined” to do anything. People who accomplish major deeds often just have the right combination of circumstances, luck, tenacity, and ability. Arguably only the last two are influenced by the person themselves. Taken together, the problems with pre-destiny and automatic right/wrong might go under the header of “sophistication.” More sophisticated novels (or movies) will tend to recognize and/or deal with these problems. Less sophisticated novels (or movies) won’t.
If you’re interested in Harry Potter, A.S. Byatt’s “Harry Potter and the Childish Adult” is worth reading.