I think the issue wasn’t just bringing back Palpatine, but by extension killing him again. How are you going to convince people he’s really gone this time?
Yeah, that’s why speculation/rumor turned to the Force Ghosts having something to do with it. Seeing his SPIRIT get snuffed out was probably the only way you could say “okay, he’s gone.” But that wasn’t the way they went with it, and there weren’t any ghosts on the scene.
It’s part of the bizarre disconnect, because everyone who follows these films seems to have a pretty general understanding of story and myth as it is, and even if they couldn’t overtly articulate WHY they expected certain things, the setup FOR those expectations is right there in the scenario. If you’re bringing back a bad guy from the dead at the very end of a story thoroughly populated with heroic ghosts, it’s more or less begging the question of how those ghosts are going to have their part to play in FINALLY, COMPLETELY defeating this old villain once and for all.
Honestly, having Kylo sacrifice to trap Palpatine as a spirit with no body, and then ghost Ben and Anakin teaming up to ensure Palpatine’s ultimate eradication isn’t even a huge creative leap. It doesn’t make any sense why it wasn’t even considered or pursued.