.. and you don't seem aware that Disney's so-called "liberal agenda" was a corporate decision going back to the decade when Disney was in sharp decline and more and more criticized abroad for being too much a mirror of American conservative social values. It had let itself get distanced by the social changes that were progressing slower in the USA, and abroad it stopped being seen, as it was in the days when the rest of the west was still also more conservative culturally, as the "safe and reliable" company in which hands you could place your children blindly. More and more parents were questioning the cultural values Disney products passed to their children, which were at odds with theirs. They used to be all over the place on TV in the 70s-80s, now they had more and more problems selling their shows outside the US, their theme parks were doing more and more badly.
It's when Disney adjusted, modernized the way they represented women, opened up to other cultures and eliminated the stereotypes more and more, in the hopes of regaining their foreign markets, and more liberal America that was also slipping away from them. They made a pretty fantastic recovery, and though they're still criticized the stigma that Disney had turned into a conservatgive brainwashing machine is gone (these days they are more criticized for their invasive merchandises).
Of course, this is balanced out by criticism from the US conservatives now, but that's largely and in fact almost uniquely a US phenomenon. Like I said we haven't seen much discussion of Disney being PC with TFA, and when we did it was usually to bring up the criticisms it sparked in the US.
The other point is that Disney gets a lot of grief for being PC with the new SW, but this conveniently ignores the fact that this is hardly new for the SW franchise and it goes all the way back to the first movie. Lucas wanted a more international cast for ANH, but he did not manage to get it. It wasn't easy to get foreign actors who could play well in American English back then and even less to find some in the pool of "super-white" Hollywood which had little diversity to offer for cheap. He first offered the role of Obi-Wan to Toshiro Mifune, who turned it down. He considered making one of the heroes Black (Solo), Asian (Leia) or alien (Solo again), and in the end it didn't work out. He tried to remedy that in the second movie, but again ran into logistic problems (hard to cast Asian or Black extras for the rebels in Northern Europe...) - but he had Lando Calrissian, for whom, if you'll recall, he got much grief because the black guy initially betrayed his friends, and in the third movie, redeeened, wasn't "upgraded" enough to a main role. Lucas also tried to show some diversity with extras on Cloud City, as he could more easily cast the extras for that (in England).
While Star Wars was heavily inspired by Buck Rogers and Flash Gordon - in essence pretty sexist and even exploitative, Lucas always intended the turn the female character stereotypes from these space opera on their heads with Leia. He wanted her to be the brains, and the leader and an action hero too, and to make fun of the whole Disney princesses and damsels in distress tropes. Rey is merely a step further, becoming the central protagonist this time, but it's something Lucas started in '77 long before it was fashionable to do that - and this was saluted as groundbreaking then (before causing disappointment with ESB and ROTJ as Leia had created expectations that were not fully met).
As for the Empire, it was intentional that they would be an all human, an all white (and British) entity in opposition to a population of diverse humans and aliens which they oppressed and enslaved. Some saw that as making a not too subtle political point, and Lucas didn't deny this, but pointed out he it was background stuff, not a political agenda as such. He had based, and willingly said so back in the day, the Empire in part on the Nixon era Republican party, in part on corporate Hollywood, and for the imagery on the Third Reich. How the Republic fell to the Emperor who manipulated the corrupted politicians and the greed of the commercial empires and turned the people who had grown complacent with democracy and lost interest in the common good against the Jedi was all there in the novelization of the first movie (and even more explicitely in that of ROTJ). SW always had a subtle anti-Republican and progressive message, reflecting Lucas's own values.
For the prequels Lucas went further, casting internationally now that he could afford it. Naboo had plenty of human races, so did Tatooine and Coruscant. Boba Fett was played by a Maori, the second Queen on Naboo was Indian. If anything, the new movie is a step back, with less diversity in both humans and aliens, though this time around they have more central roles.
That's for the SW tradition. Then we come to JJ Abrams, who's another who has a long track record of loving to have non-White, non-American characters (and even many non English speaking ones...), and also loving to get away from stereotypes for his female characters, often turning them into pretty physical heroes but not only that... he just made them as diversified and as important as his male characters. One only has to think of Alias, with two out of three of the initial main players being female, one of them black - and plenty of diversity with the other players. Then there's Lost, of course. An agenda, or just how Abrams likes things to be in his storytelling?
So between the long SW tradition and JJ Abrams's love for having a diverse cast of characters often centred on a female lead, it's pretty reductive and quite possibly completely wrong to blame Disney's "political correctness" for the fact Abrams decided to cast a woman, a black man and a latino as his main characters. In 2015 this should hardly ruffle any feathers anyway, which by and large it didn't, except a bit with conservatives in the US.