With TFA, whether Kylo was injured beforehand or not, it makes little difference in the impression his defeat leaves on the audience. Watching Kylo Ren flop around in the snow is a fast way to undo any sense of menace or threat surrounding the character. The film goes out of its way to set him up to lose the fight. The question is, what purpose does that serve to the story? What difference would it have made if the fight had ended from the crevice opening without there being a clear winner?

As for TLJ, Kylo didn’t leave Rey to fend for herself. He was unconscious. Rey wasn’t. Another issue is the fact that Kylo was visibly struggling against the Praetorian guards and had to be bailed out by Rey, who had noticeably less trouble taking them out.

As for Palpatine, I remember as far back in 2012, when the EU was decanonized, that a lot of fans pointed to Dark Empire as an example of a particular low point of storytelling, and used it as proof that the old EU was junk. Then, when people criticized TFA and TLJ, defenders of the films again pointed to Dark Empire as evidence that the new Canon was better. Choosing to copy Dark Empire, and making basically a worse, watered down version of it, was really not a good decision.

Edit: And I almost forgot Rey turning Kylo’s mind interrogation back on him in TFA. There’s a pretty consistent sense in TFA and TLJ that Rey is simply a superior Force user to Kylo.