I guess I don't get how it could possibly be PC. Isn't political correctness when you do something to avoid criticism of favoring a certain race or gender? Was anyone actually offended in 2014 that there were no female Ghostbusters in the world? If they had done a remake with men, would anyone have said "Sexist pigs not casting women as the leads"? No. Nobody would have given a freak. It's not PC to decide to make the movie with women.
They didn't change any characters. They didn't have Peter Venkman suddenly as a woman. They made a movie with a ton of similarities, but it's way different than actually rebooting with Shaft or Blade as white guys. How would you even do that with Shaft?
I have no clue why they made them women. It sure as hell didn't help the box office, which they knew. I don't think they counted on the most overblown reaction of all time to the casting news, though. Paul Feig likes directing women in interesting roles and yes, pushing the boundaries of what women are allowed to do on film. For the most part, it works. I guess I just don't see the problem when the movie works and isn't in your face about the fact that it's all girl power and whatnot. I don't see a problem with giving new opportunities to actors that haven't had them if it works.
The new IP thing is a whole different discussion. As long as the box office depends on outpacing piracy and drawing people to spectacle, you'll see familiar projects designed to draw early crowds. Until Hollywood gets out from under the theater obligations, you won't see new excrement direct to digital either. Just recycled excrement on screen.