Star Wars: 10 Massive Plot Holes The Prequels Stupidly Created
9. Why Did Palpatine Want To Turn Luke When It Would Lead To His Death?
On the face of it Palpatine's plan in ROTJ makes a lot of sense; trick the rebels into an ambush, turn Luke to the Dark Side and be home in time for Jawa juice.
The plan to turn Luke into a Sith was the main drive of both Empire and Return Of The Jedi. At the end of the battle on Cloud City, Vader not only reveals his identity to Luke, but also his plan for them to overthrow the Emperor with him (and unlike his plan in ROTS with Padmé, it feels a little less made up on the spot). From what we've learned about the Sith this is a natural thing to happen and no one should know this better than Palpatine.
The general rule with Sith is that the Apprentice's do eventually kill their master, just like Sidious did with Darth Plagueis. He's already gone through at least two learners and has militantly followed the rule of two set down long in the galaxys past. Why, at the point when he can gain full control does he break it and introduce a new variable that very likely could lead to his undoing? What was once a logical evil plan becomes bogged down in complications.