I'm... completely fine with him not doing the source material justice. Fairy tales and stories change with time and culture. Different lessons and purposes are used by different cultures based around the same technical story structure. There is nothing sacred about the various source materials as this very thing has happened time and time again across the globe. At the very least he has immortalized various motifs and themes that other media seems to have fallen off from.
The reason why the Hunchback of Notre Dame, in particular, bothered me, is because of the treatment of the disabled and other maligned groups.
The original novel gave us something I've never seen anywhere else. The Disney version doesn't. It isn't about "original," as in "what came first," so much as the narrowing of narratives. And, because Disney is so popular, the novel dies, the film grows strong, our culture loses something that it really needed... we gain something that we need in a different way.
Or, if you want me to put it differently:
I need that book. I don't say that about many things, but it's a book that I found I really needed. And when I want to find other people who really needed that book, it becomes harder to do so. Because all that most people know is the movie.
Better than the Phantom of the Opera, which has been twice-killed--the first time by the musical, the second time by a knockoff novel by Susan Kay, named Phantom, which is preferred by many fans. It's glorified fanfiction.
I guess that maybe it's just me being petty, so that it's about me for once in my arguments. Well, I allow myself to do that sometimes, and this time I'll just say:
I feel that Disney has been instrumental in taking away some of the culture that I needed to feel safe in the world, both a beloved novel and some fairy tales I read as a little girl. I needed them, and I needed their cultural effects. I wish, more than anything, that we could have both.