Each of the Star Wars trilogies are very much a product of the era which they were created in. The villains represent the fears of their time, at least from an American perspective, and the good guys are a reflection of how America sees itself.
The 70’s were right in the middle of the Cold War, Eastern Europe had fallen behind the Iron Curtain and both the US and the USSR had enough nuclear weapons to wipe out all life on earth several times over. The Soviet Union was very closed off to the West so the average American citizen knew very little about the USSR beyond that it was a communist totalitarian regime with a powerful military and expansionist desires. The Empire plays on the fears that most Americans had during the Cold War. Cold, calculating military leaders like Vader and Tarkin stand in for the Soviet military elite while Palpatine is a Stalin-like, cruel, totalitarian dictator. This was very intentional on the part of George Lucas as in the deleted scene featuring Luke and Biggs from A New Hope, Biggs mentions that the Empire had begun to nationalize commerce in the inner regions of the galaxy. The Death Star with the power to destroy a planet represents the fears of nuclear war and mutually assured destruction.
The rebels then represent how America saw itself during the Cold War, as the champions of freedom and democracy and the only thing standing in the way of the spread of communism and totalitarianism.
The Prequels of the late 90’s and early 00’s also reflect the self-perception of America at the time. (Even if Lucas had hired Lawrence Kasdan to write the scripts and had hired “actor’s directors” to direct, I think the prequels would still have rubbed a lot of people the wrong way simply because they hit a little too close to home.) The Republic was praised in the Original Trilogy as the democracy that the Rebellion was fighting to restore and as a “more civilized age”, something that Americans liked to identify with, but when we actually see it, it isn’t so ideal. The Galactic Senate is mired in corruption, bureaucracy, and political infighting much like the American government. The Jedi are essentially a self-righteous galactic police force serving at the behest of the Senate. This draws parallels to the criticisms that began in the 90’s and continue through today that American sees itself as the “world’s police”.
Palpatine’s rise to power also plays on the fears of the early 00’s that the government was taking too many freedoms from the people in the name of security. When Revenge of the Sith was first released many comparisons were drawn between the scene where “liberty dies to thunderous applause” and the passage of the Patriot Act.
When The Force Awakens was being written the biggest fears were fanaticism in the form of terrorist groups like ISIS and lone wolf shooters. This is why the First Order is shown to be far more fanatical whereas the Empire was portrayed as cold and calculating. It’s also possibly why the army of the First Order is composed of those that have been brainwashed. Kylo Ren fits the profile for a school shooter perfectly: a kid from an otherwise good family who has some serious mental and emotional issues, feels like an outcast, and wants to be feared and respected. Heck, replace “shooter” with “stabber” and this is literally what Kylo Ren is considering what he did to Luke’s other students. (I’ve heard fans say they don’t like Kylo Ren as a villain because they don’t think he is scary enough or that he doesn’t have the presence that Vader had. I would be curious to see how those opinions correlate with age.)
While not shown in The Force Awakens, Rian Johnson’s input into the novel Bloodline was the political situation of the New Republic and the Napkin Bombing. The political situation being that of a widening gulf between two parties who refuse to compromise leading to government deadlock, much like the current American political situation. The Napkin Bombing plays into our fears of the small scale terrorist attacks and mass shootings that have become all too common in the US and Europe in recent years.
We’ll have to wait and see what Rian, J.J., and the story group have in store for us, but I expect that it will continue to be politically and culturally relevant as that is part of what allows these stories to resonate so well with audiences.