Uh, John Stewart was created back in the 70s in the actual Green Lantern comics and chosen for the JL cartoon, probably for the diversity reason in both cases.
Yes, I know that. I didn't say "he was... created and used in the animated
Justice League" -- I said "he was... created, and used in the animated
Justice League, etc." Note the comma; I cited his creation in the comics and his use in JL as separate clauses, separate events. Although I could've conveyed that more clearly, true.
And my recollection is that before JL came along, John Stewart was considered a secondary character in the comics. That's why, when Hal was killed off, they created a new (white) character, Kyle Rayner, to replace him, instead of just promoting John to the lead. The reason John Stewart is equal or greater in popularity to Hal Jordan
today is because the producers of the JL television series decided to make him the GL for the sake of team diversity, and thereby gave him far greater exposure than he'd ever had before. The simple fact is, the number of people who read comic books is a tiny fraction of the number of people who watch television or movies. So a character's use in a screen adaptation is going to have a huge impact on that character's popularity. This is why characters like Harley Quinn and Renee Montoya, who were created for television, ended up becoming major figures in the comics.
Or differing attitudes towards racial choices from theatre fans to comic book fans, take your pick (I do remember when I last was in an argument about this on the TrekBBS, some time before Thor's release, there was a guy with a Confederate flag avatar dead set against Elba). Opera's also pretty colour-blind, in a manner that cuts all ways - black tenors in white roles, white tenors as Asians, et cetera.
I think theater folks on the whole are generally an exceptionally tolerant bunch; look at how much gays and lesbians have long been accepted and welcomed in the theater community.
I can understand how, especially with a visual medium like comics, people are a little disappointed when the movie comes on to the big screen and characters look different. But you're always going to get that. Tobey Maguire didn't look exactly like Spider-man nor Ben Affleck like Daredevil among many others. Hugh Jackman looks like Wolverine to me, but he's a foot too tall. The bottom line is, he captures the essence of the character for me and thus he works.
Honestly, Jackman doesn't capture the essence of Wolverine for me. Not just because of his height, but because he feels like Wolverine reinterpreted as a handsome leading-man type, toned down and spruced up from what he is in the comics. Which works for how they've handled him in the movies, but it just feels like a different character to me.
Now, I would accept that with, for example, Captain America or Batman, having a black version might be incompatible with their history and background. That is, Cap was created during the second world war, when there was segregation in the US Army and black soldiers were treated more poorly than their white comrades. So, if you had a black Steve Rogers, realistically, he would not have been the visual focus for the war effort the way he was in the recent movie, white officers might have been loathe to obey him etc. You would have had an interesting movie but quite a different one.
It could've fit the origin story, the tale of a man that nobody thought was worthy to fight alongside them until Dr. Erskine recognized something in him and gave him a chance to prove himself. Would've been an interesting twist if he'd been deemed unworthy because of his race rather than scrawniness and poor health. But you're right, it would've significantly altered the rest of the story.
Similarly, I think that it might not convince people that you could have a black Wayne family, who were scions and patrons of Gotham for years. Are there many wealthy black families, who have been as powerful and wealthy as the Waynes? Would many black families have had an English butler in their service for years? (Okay, there aren't too many white families like that either, but I'd imagine more white ones than black ones). I remember reading that the grounds that became the Batcave were once used as an escape route for runaway slaves, facilitated by the Waynes. Again, this might be interesting if the Wayne family were black, but it does make for a somewhat different situation.
There are a number of wealthy African-American families, though it's true that mostly it's a recent phenomenon; the first African-American to be worth more than a billion dollars was apparently Reginald F. Lewis, the founder of Beatrice Foods, who reached that point in 1987, about a generation ago.
So it might require revamping the background a little, having the Waynes be first-generation multimillionaires who achieved their wealth through their own labor rather than inheriting old money. I think that could actually be better in a lot of ways, would make them more admirable and give them more of a self-reliant work ethic that they could've raised Bruce with.
After all, the core of the Batman story just requires Bruce to be rich and live in a mansion that's conveniently built over a large cave. There's nothing that requires his wealth to be old money or his family to have been part of Gotham's elite for generations; those are things that have accreted onto the story over time, details that could easily be set aside in an adaptation because they've rarely come into play outside the comics and not often within them.
On the other hand, I could see no reason why, e.g Spider-man or Daredevil couldn't be black. They come from poor parts of New York. They're working class heroes. Spider-man is bullied at school - could it be in part down to his being one of the few black kids there? Why not?
Of course, in Marvel's
Ultimate Spider-Man comics (little or no relation to the current TV series of that name), Peter Parker has died and the role of Spider-Man has been taken over by Miles Morales, a black-Hispanic teen. So yes, it certainly can work, and to all indications
is working quite well.
And, let's face it, in the movies, there was no mention of them having been Gotham aristocrats for years or having been part of the slave railroad, etc.
I think the Underground Railroad tie (tee-hee) was mentioned in
Batman Begins.