I mainly dislike Rose because she tazered Finn, thus derailing him from a more interesting storyline, and essentially hijacking his arc to preach to a former child soldier about oppression.
Finn’s demotion from co-protagonist in TFA to being confined to a filler D-plot in TLJ is something that will always rub be the wrong way.
Edit: Now that I think about it, the issues with Luke in TLJ are very similar to the issues with Superman in the Zack Snyder DC movies. The notion heavily implied in Snyder’s movies, that if Lois Lane were to die, Superman would basically lose his marbles and turn against humanity, is absurd, and shows a lack of understanding of the character, his resilience, and the strength of his convictions. It’s antithetical to Superman. Besides that, his lack of an emotional response to the mass destruction caused by Zod and himself during the final battle in Man of Steel, makes him seem completely lacking in empathy, since any ordinary person would be horrified by the death and destruction around them. The fact that he feels more upset about killing Zod than about all the civilian casualties during the battle, makes it seem like he lacks a strong emotional attachment to humanity, which is ridiculous, since he’s essentially human in every way that counts.
TLJ doesn’t humanize Luke, in the same way that Man of Steel doesn’t humanize Superman. They were already human.