Originally Posted by endurell
Then I guess we have to ask ourselves what the heck obi-wan was smoking in episode IV...
"And these blastpoints, too accurate for sandpeople. Only Imperial stormtroopers are this precise."
obi-wan intentionally sacrificed himself in episode 4 because he would be able to help luke more as a spirit. Plus it was necessary to make Luke fulfill his destiny. If you watch the movie its clear that he does it intentionally.