Eh, I think we just have different perspectives on things being short horned. In my view, anything that isn’t critical information to the story, it’s shoehorned in. If you tell me the main characters favorite food is pasta, and then don’t do anything with it, it’s shoe horned in. If you tell me a character is gay, and then don’t do anything they couldn’t have done the same with a straight character, changing a couple of pronouns, it’s shoehorned in.
To be clear though, I don’t think this is a bad thing. A story with only critical information will… Well, it’ll work, but it’ll be bland. Same if you make all of your characters blond, blue eyed, straight white men. Adding these details tends to be what makes us remember and identify with a character. That doesn’t make it any more strictly relevant to the story. Most characters people would view as “diverse” - even the ones people like - fall into this category, i think.
I think a better argument is, if these traits ARE shoehorned in, their alternative “normal” traits would be as well. If you go out of your way to state a character is straight, it’s just as shoehorned if everything else is equivalent. Do THOSE characters inspire the same ire? If not, we should examine the why of that specifically.
I mean, movies have existed without sound at all, so yes, I’d classify music as typically not essential, unless the movie is ~about music~. Same with the movies you listed, they’re about the character growth and development, not a bigger plotline (I assume,I actually haven’t seen them).
In order to tell an effective narrative, certain pieces MUST be there. These are the story. Anything else is fluff, filler, not essential. You can play around with all of that, get something that looks and feels different, but is the same basic story. Remakes and AU style things do that all the time.
As far as the blond, blue eyed thing - I didn’t say it was describing the default human. It’s describing the default within American pop culture. The default movie hero is, and I’m spitballing here, a 30s-40s straight white dude. And, like or not, American pop culture is world pop culture. America largely defines the trends in pop culture worldwide. I don’t think this is a good thing, for the record, but it’s also not a crazy statement.