(Warning this could get very political very fast)
Sky are producing a new adaption of The Midwich Cuckoos that appears to have more than a few questionable departures from the source material.
One of the key points to the story is that all of the Children (The capitalisation is important) look alike. In a weird and creepy fashion that makes it obvious that something strange and un-natural is responsible for their births, and they cannot possibly be related to their mothers, or any possible human father.
Only this version appears to have gone for diversity casting with the Children.
No one is saying that they have to be of any specific racial group, but again one of the key points to the story is that they all have the same un-worldly origin and have similar characteristics. The violent reaction to "The Other" is one of the story's themes, and the initial reaction of cultures other than the main setting is also important. (Which is essentially kill it).
A diverse casting for the Children is questionable in more than one way as they are explicitly cuckoos. The Children are parasites, which might be a slightly dodgy way to present diverse casting. And if you take the story to its conclusion, not immediately killing "The Other" is shown to be a bad idea, an accepting culture being more vulnerable to, probably, alien infiltration.
[Please no one take this as being that I am somehow against diversity, or start calling me racist. I'm pointing out that the production is being un-faithful to the source material, and in a way that is obviously pandering to modern sensibilities, to the extent of compromising the story.]