You shouldn't compare the number of physical comics sold with movie tickets sold, that's not the right comparison. It's people who consider themselves fans of the character, before the movie, vs movie tickets. I'm a fan of Superman, I've never bought a Superman comic book in my life (for the record, the only comic I collect is The Rocketeer). Lots of people have prior experience with characters, enough to know when a production feels "off". This is of course more true with Superman than say, Captain Marvel.
Except most of those people's familiarity will come from TV and movies, so they won't necessarily know what's true to the comics.
More to the point, racists and sexists are always using "fidelity to the comics" as a cover for their hate, so it's dangerous to assume that's genuinely the primary driver. I mean, it's obviously BS; they never object when Jimmy Olsen is portrayed as blond or brown-haired instead of red-haired, but they always trot out the "fidelity" argument when he's depicted as black.
The way I see it, toxic negativity can't a get a foothold if the show is actually good.
Nonsense.
The Marvels was fantastic, but the negativity absolutely got a foothold there.
There's no clicks in trashing a show people actually like.
That's completely backward. The whole reason YouTube haters focus their hate on popular, successful shows is because that gets them more attention. There's plenty of hate directed at
Star Trek shows and movies that are actually pretty good.
Star Wars and others as well. If people don't like a show or film, it gets little attention, so there wouldn't be that much interest in criticisms of it.
Besides, in my experience, anything that is strongly loved by some people is going to be strongly hated by others. They're two sides of the same coin. The only way to offend no one is to delight no one, to be too mediocre to generate much reaction either way.
But how are you defining "realistically"? Are we making allowances for setting, or does the cast need to match the 21st Century SAG?
People always cast this issue in terms of the characters, but that's missing the point. A TV series or film is an
employer. What matters is whether it's open to hiring actors, creators, and production staff without bias, in which case the cast and crew will naturally be diverse. How the characters are written and depicted is a response to how the cast and crew are chosen. If the cast is diverse, then the characters will be. (Of course, that doesn't have to be the case in animation, but these days it's generally preferred for actors to play characters of their own ethnicity.)