I don’t know. I think it’d be fairly easy to disguise yourself around the galaxy. Wear Mandalorian or Booush armor. In Kylo’s case, grow a beard and cut your hair. In Vader’s, no one knew what he looked like under the helmet. This would be helped with Luke/Rey claiming they are dead.
The problem with immediate death is it isn’t very interesting. Vader and Kylo never confront what they have done. Love should be used as the tipping point back over, but once on the light, it would have been nice to feel some remorse for their actions.
And I think all of this is well and good, but it’s also going back to that fundamental question of what “Star Wars is about” as if there’s a central unifying thesis behind all the storytelling decisions being made (I don’t think there really should be) as opposed to Star Wars being defined by its look and sound (which I think is the most unifying aspect, and probably should be)
Except now you’re the one placing limitations on story potential.