I think this is a great way of describing it, when you say emotional resonance. Words like 'substance' and 'depth' might translate in way different ways to different people and also I think imply some feeling of fake importance to things. Importance behind what an individual sees in a movie.
Personally, most movies that are widely said to have depth, I don't really see anything in them beyond what I might or might not see in movies that are usually said to have no depth. Emotional resonance I like, and I equate that idea with things being true, which of course I don't mean similar to reality in a logical sense or even 'grounded' but internally true to themselves and also true to what I see as the forces that drive a person and how these forces, in turn, working from different people, drive events and conflicts. And that exaggerated and altered is what creates drama.
So with that definition when I look at something like TDK, I feel like the Joker is true. There's something perfect about that performance and the way that version of the character was written and what he was supposed to mean in relation to Batman. But in most other ways, I see TDK as being pretty false and empty of real human character behind any of it's 'characters'.
The kind of depth most people seem to see in things like it, to me, just comes off as vague shapes of abstract concepts expressed with lots of keywords in expository dialogue. And it's just doesn't mean much to me when something's theme is said to be Fear. What does that mean? What about Fear? I don't even think there's anything to say that's very interesting just about Fear in the abstract or Chaos or Redemption. That's just cheap sloganeering in a modern package, and it doesn't make something deep. Say the theme of a movie was how Redemption is only found thru Sacrifice. That means nothing. That's what I've come to call 'themey'. And it seems like for comic book movies, it's some kind of trend now that things have to be about some dumb thing.
What actually means a lot is hearing, reading, seeing a story that plays that out in a true way. And that can give me a lot of insight and a new of looking at things that I'd say was genuinely deep, for me to realize. Random examples of movies like this to me are La Strada, Mulholland Drive, Dracula, Dawn of the Dead, Let the Right One In, Battle Royale, Cocteau's Beauty and the Beast. They aren't really about anything and they don't toss up topical issues just for the sake of that they are an issue that people like to talk about. Like a movie about genetic cloning in the future or wiretapping and privacy in TDK. People seem to think that depth or substance also comes from whatever things they read about in the newspaper. Whatever is modernly trending seems to be what most people attribute substance to. A thing's worth is more tied to it's success in capturing some aspect of human experience tho, which isn't gonna change anytime soon. That's why Greek myths are still so crammed with substance, it's all stuff that's lasted purely becuz of that, not cuz of themes and key words, but instead the actual forces at work in the world.
And what you're saying about emotional resonance is a better way of saying it and looking at it, becuz the real sense of meaning we take from these comic book movies is largely what we bring to them. Superheroes are especially good at providing blank canvases to project on. And this is why we always hear people who love DC saying that they think Marvel movies are less meaningful to them and vice versa. Cuz you aren't invested in what you don't know. I love Spider-Man, so any of his movies are gonna affect me in ways that someone who hasn't grown up obsessing and loving this character isn't going to understand. I don't care about DC (except for Superman) so if I see a Batman film I can loved it as a part of the genre but Bruce Wayne's whole schtick of problems comes off as kinda gross to me. It's not that I hate Batman or DC, it's just that I don't have any love for the characters.
What I'm meaning is that emotional resonance is something that more admits that this is totally subjective. And also it takes the focus of things being about something or trying to make some obvious and tired point or having a moral or having to present a major transformation on a journey to full circle with a character and it actually focuses it on what people watch movies for.
Cuz movies aren't books, they're speaking visually and that's where it's power is. Movies like TDK, I think, do have genuine substance, purely by how they look and feel and how that interacts with the characters in the movie. But for a person looking for a more defined kind of depth, how something looks is considered secondary and possibly even superficial. But it's a movie, you know?
People are always saying that David Lynch just makes things up and that his movies have no point behind them becuz they're used to this idea that the film maker controls what something means. And it's the same thing with songs. But that's not the nature of film or of music. It's actually a really wrongheaded approach to either one. What a person imagines doesn't have any less truth just becuz they can't explain it. If you could explain such things, why would u even need to make a movie or write a song about it? These mediums are for unexplainable things. Writing blocks of text like this or term papers are for explainable things.
so yeah, emotional resonance, i like it.
the last thing about this is that when we ask each other 'what was that movie about?' or 'how did you find that movie deep?', I think that's often used to somehow classify or rank or define a movie. And the question at it's best, I think, actually a question about the person who saw the movie. What it all meant to them, and what did they read out of it. So it's not really about the movie at all, it's about the person you're asking it to. And I think that's kind of the problem with how we all, to some extent, are raised to think about art.
(which doesn't imply that there's no such thing as good or bad in art. Cuz there definitely is)
Well said! This is why everyone's tastes vary so much, because most of the 'deep and richness' we feel with the movie,or any art form, is subjective because it is mostly down to our real life experiences, and sometimes even our dreams. So it isn't really 'deep and richness' as it is emotionally resonating with the viewer for a deep reason. Thus emotional resonance. 
t:
?
