I think people have complained about casting choices forever. The first female Hamlet must have gotten some negative press as well. I believe the pattern you see is based on two factors:

1. We all carry a media device with us. We are quick to respond and post stuff publicly and in return we get to read other people’s thoughts. What would’ve taken a couple of weeks to spread to enough people to make a dent in any poll in the age of newspapers can take a day or so now. So the speed has picked up. Also, the stuff our media devices serve us depend to varying extents on the use of algorithms. We know that especially in the realm of social media, user engagement is strongest with stuff that riles us up. So the old algo serves us more of that. Algorithms distort the picture. Things are labeled as viral when they are viewed by thousands of people - on a planet of 7 billion or thereabouts. Storms on the internet tend to be teacup size most of the time. The internet gives us a distorted picture where a small number of people can pretend to be a significant portion of society. And that doesn’t mean the Illuminati control this sinisterly; it can just be a few d-heads who think alike that start stirring the teacup. But PR agencies exist to make use of this as well.
2. Politics and society are not on a linear trajectory to paradise. While overall we’re better off as a species than 1,000 years ago, the way stuff moves is often 3 steps forward and 2 steps back. One could say, the US (as one example of many countries today) has just taken two steps back. A political movement that we thought was done for after we have all seen where it can lead is back: right-wing populism. It is a backlash to well intentioned political decisions with regard to equality, the eradication of racism, allowing women autonomy over their own bodies, etc. A lot of people had differing opinions about these things but social norms had confined them to family gatherings and the pub where they could voice them but not much more than that. Now they can voice them online as well and find many other dissenters they wouldn’t have found as easily just 30 years ago. And because they feel like a majority (see 1)) or a significant portion at the very least they become more outspoken. Saying the quiet parts out loud. So talking badly about people of another ethnicity, women, etc. is en vogue again. So any opportunity for that is good enough.

So Star Wars is casting a non-binary person to lead a new show? “Fans are outraged!” The new 007 is a black woman? “Fans are up in arms!” These have become predictable reactions that gain traction in for-profit media that also needs us to engage so they can sell ads. So is this a pattern? Yes. Is it new though? I don’t think so. It’s just accelerated, amplified, fueled by politics, and more often than not a storm in a teacup.

Before I finish this essay, I would like to point out two examples that popped into my head that go against the grain. Scarlet Johansson’s casting in Ghost in the Shell caused a stir. And about a decade earlier Benedict Cumberbatch as Khan from Star Trek was also met with criticism.