Very interesting topic for discussion.
I think you pretty much nailed it. It’s the style that is different. Not only the Original Trilogy but the Prequels as well were all shot in a documentary film style told most often through the point of view of R2-D2. The Sequels forget this established grammar or chose not to use this rule. They followed their own filming grammar to convey the worlds we see and explore. It’s also about rhythm I find as so much of the Sequels is about getting from Point A to B in seconds. Things don’t stay at one part of the story long before we’re onto the next plot thread. Things don’t breathe or happen gradually but instead in a way that doesn’t give us time to establish or know the environments we’re in or the characters.
The Force Awakens in particular I find is very guilty of this. It takes Finn like two minutes to get to Rey. Even The Last Jedi has this problem to an extent as it took Finn and Rose a couple of minutes once they arrived at the casino to find the Master Codebreaker as they stopped looking and BB-8 finds him. On the opposite side of things it took Han time to find Luke. You felt the passage of time and the struggle to find him on Hoth. The same thing with Obi-Wan, Qui-Gon, and Jar Jar travelling to Theed. You could feel the wonder and sense of discovery with the characters. You don’t get that sense of knowing where you are with the Sequels. The Last Jedi I find gets it right sometimes but in a different style to that of the first six films. J.J.'s films are too rushed and more like any other genetic Hollywood action film. That’s not even close to the style of Star Wars.
It will feel different because it is different. The films aren’t shot in the same way anymore. They’re shot how the director of said project wants them shot. They’re not in the established style George set up and executed.