You're so right.
Why didn't Yoda come back to fry the Emperor? If a Force Ghost can call a massive lightning bolt to ignite an ancient sacred Jedi site, why doesn't he Emperor come back and fry everyone? Where is Kenboi? Why isn't he back to fry Snoke? Rian Johnson thought, "Cool! Yoda can be as irreverent as everyone else in this movie. Risky! A new direction!" But it makes no sense.
I don't think it's true that Star Wars fans don't like this movie because it's new and different. We don't like it because it's inconsistent and stupid.
Original, first generation fans were used to Star Wars changing directions from the very beginning. After that kiss for luck as Luke and Leia swung across the bridge, a lot of us were expecting romance down the road. Brother and sister? What?? Vader is pater? What?
Millions of us read and loved the Zahn novels. Throwing that out of canon was a Huge New Direction. No functional marriage for Han and Leia? Okay. The three kids they had - gone? Okay. Luke, successfully passing on what he has learned, as Yoda told him. But he didn't. Okay. Marrying the massively intriguing Emperor's Hand, Mara Jade. Mara gone. Okay. Their son Ben gone. Okay. All okay. We swallowed that and loved FORCE AWAKENS anyway. We can deal with being surprised, with risks, with new directions. We are not limited. Unwillingness to be surprised or accept a new direction is NOT why Star Wars fans don't like THE LAST JEDI.
TLJ had no cohesion with TFA. And, as you say, TLJ dropped almost everything introduced by TFA. It felt like enormous hubris to break every promise TFA made, massive storytelling laziness to drop every thread TFA had woven, a thumbing of the nose to Abrams and Star Wars fans generally to cast all that aside.
If you go to a movie to enjoy the movie, you'll enjoy TLJ. If you go to a Star Wars movie for a story that doesn't insult your intelligence, characters who develop logically, a plot that evolves consistently with what came before, a film that feels like Star Wars (which, for many of us, all the others did -- different in tone and quality as they were) - you might be disappointed.