While there are many reasons for this, one of the most prominent is where the money lies.
If you think back to when franchises like Star Wars and Ghostbusters came out, the people who had money to blow were rural people. Which you can assume were mostly righties.
In today's world, the people with the money, and time to blow, are urban people. Which you can assume are mostly lefties.
While for the large majority of righties, race or gender don't matter, and simply being the best available in what you do matters most. While for many lefties, it seems that overall inclusivity matters more so than being great at specific tasks. This does explain to some extent why lefties tend to be more creative than righties in general, yet righties tend to be more efficient.
It's no coincidence that media back then favored the right, while it favors the left now. To make matters worse, the time and effort that rural people must invest to remain middle class, is much more than it ever has been before, and much more so than urban people. The rural people, even if they have the money, don't have the time for movies and tv like they used to, and tend to forget/avoid it completely since it can't fit their lifestyle, and they find other things to spend their money on.
There is also the fact that back then, men were the ones working for the most part, so pleasantries like media, were designed to give them relief from their work day. In today's world, there are many more woman working than ever, and the media is trying to cater to them as well. Add in the political divide, and it's not really a shock that certain media and certain companies/franchises are taking sides and sticking to them.
Luckily we human beings have been designed to cope with this type of thing. We have the ability to adapt in many ways, but if we can't, or simply don't want to, we also have the ability to be able to travel great distances to start anew and make things the way we want them to be. The same still applies today, minus the fact that all hospitable landmass has been found and claimed on this planet, so aside from "war", you have to pick a country with the rules and lifestyle that fit you the best, and go from there.
Life changes, and it isn't fair. Learning to let go and start over is part of process, unfortunately.