Obi-Wan can communicate telepathically with Luke and appear to him as a ghost. Isn't this enough for him to keep training Luke? Why does he only communicate with Luke only two more times? Is there some sort of limit to how much you can communicate with the living as a Force ghost? Does he have more important things to be doing in the afterlife? Obi-Wan's promise of "becoming more powerful than you can possibly imagine" seems like a big letdown since he hardly uses his powers over death afterwards. In reality, I guess we were limited by Alec Guinness's desire to have a small involvement with sequels to Star Wars. Speaking of ghosts, did Luke tell Leia, Han, etc that he had visions and heard voices of a dead man? He would seem pretty dang crazy, especially with Force skepticism so rampant those days.