I'm in the exact opposite camp. Episode VIII wasn't a perfect movie by a long shot but it was an improvement over Episode VII. Besides being a near copy/paste of Episode IV in some places, it didn't do a good enough job building up the new characters that were supposed to be at the forefront of the new trilogy. Kylo Ren seemed like a poor man's Anakin Skywalker with a disappointing amount of screen time, which while comparable to Vader in A New Hope, that film also had Tarkin to serve as the real main villain so we could learn who Vader is an respect him as a bad guy for Empire.
Poe Dameron is another problem. Disney has treated him like the new Han Solo, but of the "main" characters of the new trilogy, he had the least amount of screen time and pretty much sat out the second act entirely, not to mention most of the first as well. If one wasn't reading his comics that came out after, you'd have no clue who this character was until Episode VIII.
Episode VIII sold me on both Ren and Poe as characters, finally giving them enough screen time for the actors to flex their muscles. Not liking their characters is another argument entirely, but at least you can tell what their characters are at this point.
Now we come to the supposed ignored "Set Up" from Episode VII into VIII. The Force Awakens didn't set up anything that The Last Jedi didn't deal with in some way. Rey is on an island to train with Luke to help the Resistance. We got that in spades. Kylo Ren is falling further to the dark side by killing his father, seeming to banish the light from him entirely. Snoke is a new puppet master, a Sidious to Ren's Vader. Except instead of blatantly retreading more of the same ground like Abrams did, Johnson wisely nipped that in the bud by cutting Snoke in half so Kylo could get out of the shadow of his grandfather and be his own, new villain. I can understand not liking the way some of this was handled, but the set up was in no way ignored at all, since the set up we got by the end of the previous movie was vague. The deal with Rey's parentage was really done and settled with in VII when Maz tells Rey that whoever she's waiting for isn't coming back. That should've been the end of it and Rey's belated call to adventure to really go all-in. The only reason it was included in VIII is because the fans kept trying to theorize and Rian (hilariously) decided to shut them down.
And now we get the the crux of my argument and my worries for IX: J.J. is the real problem with the Sequel Trilogy and not Rian. The only reason VIII treat any sort of familiar ground whatsoever was because of where VII left off. We knew we were going to get another Degobah type story with Luke and Rey, and we knew we were ALSO going to get an Emperor's Throne Room type story because of what Snoke said to Kylo: "Bring her to me." Now, Rian could have left that for IX, but he dealt with it so that way IX could be as original as possible. With it already done, that meant the writers and directors of IX (Trevorrow at the time, now Abrams again) would have to think outside the box and do something we hadn't seen before.
Of course now we've got one-trick-pony Abrams back with his mystery box and he's recycling stuff that was thrown out at the concept stages for previous movies. I'm excited and intrigued, but his track record isn't exactly that great when it comes to his writing. I'd argue the best of the newer Star Trek films is Beyond, which he didn't direct and had no hand in writing. At least Episode VII had Lawrence Kasdan to help make the script feel genuinely Star Wars-y in enough places to escape my complete ire. We don't have that on IX. There's lots of cool stuff in this trailer, and while Palpatine is back someway somehow, there's no way it can be a complete rehash of Episode VI unless Abrams wants to prove that he literally has no original ideas. Because of how VIII turned out, it's going to have to do some things new and exciting... I hope.
And of course no matter how the movie turns out-
This statement can't be further from the truth. People like Dave Filoni and Jon Favreau are going to keep the heart of it alive with projects like The Mandalorian and Clone Wars Season 7. These big shot directors will come and go, but what many consider to be the gooey nerdy heart of Star Wars will remain intact for years to come thanks to people at LucasFilm like them. I've been saying it since about 2012, but the modern era of Star Wars is best on TV (and streaming services). Not to mention games, novels, etc.