In the Star Wars Sequel Trilogy they shouldn't have had Palpatine come back alive. It didn't make a lot of sense to me.
It is already canon in that universe that when a force user dies, they can talk to and influence their padawan learners from beyond the grave, or appear in a ghostly form to them.
Why didn't they just do that?
Imagine if Rey and Kylo Ren were both hearing Palpatine throughout the films, maybe not even knowing who it is.