"Chekov's Gun" is a perfect example of assumed or inferred expectations without intent, with regards to this movie.
There was no Chekov's Gun. But people were so convinced that everything had to mean something in TFA, and everyone had to be related for some big reveal, that they saw Chekov's Gun's where there were none.
And yes, character moments need to be earned, but not every plot development or revelation needs to be telegraphed a mile away. That removes their impact and surprise. And all the big "reveals" in TLJ may not have been foreshadowed in TFA, but they were all setup within TLJ.
TLJ is incredibly character driven. It's about discovering who these people are. I've seen people say that is an excuse for not having a plot, but that is the plot. It's just maybe not something you've seen so much focus on in a Star Wars movie before. (With the exception of ESB.)
Finn's journey though this movie is him leaning to stop running from something and deciding to fight for something. It's his journey to becoming a hero.
Poe's journey is to learn to be more than just a cocky fighter pilot and learn to be a leader.
Rey spends all of TFA assuming that answers will be just handed to her, and that her parents, or Han Solo, or Luke Skywalker, will just swoop in and save the day and instantly make everything better. In TLJ she finally learns to take action herself, and that maybe the world is more complicated that she thought. It's her journey towards being the self actualized hero.
Kylo's journey is about going from being a "Darth Vader clone" to his own person. He kills his "emperor" and is now in charge of his own destiny, in a way that Vader never was.
All of those moments are earned throughout the course of the movie. Every reveal or twist is about character. And they are earned by those characters.