From my point of view, everyone against me is evil!
Agendas definitely exist, but it depends on the "creative piece". After all, they all exist to pass on the writer's/director's/artist's ideas on some topic, at least on some level. Peele choosing to make his movies with a predominantly black cast isn't an "agenda" in the sense that he's trying to promote something. It's just what he's interested in doing. The films themselves, as all films do, pass on some kind of message that he wants, through the stories and so on and so forth. Wes Anderson choosing the casts that he chooses is also not an "agenda"; he just likes working with those people and finds them working with his directing style. Again, whatever message is passed on through the films is another matter. If we diverge from those two, the casting in, say, the Expanse is not an "agenda". The playable characters in GTA V weren't an "agenda". And so ona nd so forth.
When it truly becomes an agenda, is something like BBC's Troy miniseries, which took Greek myths and inserted blacks in our very central stories. Aside from being historically, or at least canonically innacurate, it was also quite an insulting move. What is an agenda is the recent Mary, Queen Of Scots film where half the Court was played by Africans, Asians and whatnot. What's an agenda is the upcoming Netflix movie (or it could be series) about the Lady of the Lake where Arthur is black. You get my point.
You want to make Vigilante black? Sure, whatever, it's a fictional creation set in the [current year] (sliding timescales and all) and comes from funnybooks. I'll say "why do it" and they'll respond "why not". And I'll say "but why" and they'll say "but why not". And on and on it goes. Because, ultimately, it's not specified anywhere that the American under the mask must be this guy. I'll always think of Adrian Chase as a blonde guy, but if the rumous are true and Idris Elba is playing him in the new Suicide Squad film are true, it makes little difference. But you cannot make Daredevil black, since he's specifically an Irishman with tons of Catholic guilt. You can't make the Punisher black because he's specifically Italian. Even then you could twist them around and just make them generic something-Americans and be done with it.
But cultural myths and stories aren't cape****. When I see a black Achilles and some **** from New York is lecturing me on how "Homer" totes was onboard that ****, it infuriates me. That's an agenda. For what? That's a different discussion for a different type of forum. But I just want to say that Peele's films aren't agenda-driven in that regard. They're the films he wants to make. Same with Wes Anderson or even Spike Lee. Will I ever watch Peele's or Lee's films? So far I can say "not really" because the subject matter doesn't appeal to me. I simply don't care (Inside Man was good though). But that doesn't have to do anything with the people themselves, as they're just making the films they want to make, with the people they want to make.