Why does "diversity" need to infect every movie and TV series?

Recently I started watching the 2014 TV series The Flash. It's not exactly a mind-blowing work of art, but it's passable, mostly innocent fun.

However, from the very first episode you immediately start seeing the modern "inclusive" touch on everything.

While they didn't dare to change Barry Allen himself from the comics, almost everything else is.

Kid Flash? Black, of course. (Wasn't originally in the comics.)

Barry's adoptive father? Black, of course.

Barry's girlfriend and fiancé? Black of course. And his stepsister to boot.

I mean, come on... I suppose biologically speaking there's in principle nothing wrong in marrying your stepsister, but sheesh. There's the undeniable psychological and social aspect to it.

At least they didn't have to change one of the other protagonists, Cisco Ramon, ie. Vibe, who was actually originally Hispanic even in the comics. But I feel that in this case fidelity to the source material was principally not chosen for accuracy but because the character was already "inclusive" enough. However, I suspect that they included that character in particular in the TV series precisely because the character is Hispanic, not because it would have fit the storylines so well.

But whatever, I didn't let those casting choices bother me too much. The vast majority of the episodes are, after all, rather innocent and completely free of political messaging. Perhaps a bit surprisingly, the fact that Barry's fiancé and adoptive father, and Kid Flash, are black is not brought up in any way. They just are, and there's nothing else to it. No moralizing, no "message", no politics.

Yet... the series still can't help but throw a bit of "the message" here and there in individual episodes. There are a couple of episodes that are just weird, out of place, don't really feel like they belong in the series, and seem to exist only to deviate from the actual narrative in order to moralize. For example in one of these "weird" episodes in an alternate universe the father of one of the alter egos of the protagonists is gay, and quite openly so, and it's made into a plot point to emphasize. For no good reason.

And what about all the villains? Surely the cast is equally "diverse" there? Well, what do you know, I don't remember a single one of them being non-white. What shocker. 

By the time I got to the episode "Crisis on Earth X, Part 3" in season 3, which has literal Nazis massacring gay people for being gay, I got fed up and stopped watching the series.

There's like a million other TV series and movies on Netflix to watch. I'm not going to miss this one.