Mrbenja0618:

Man, why did they kill him off? Would that not been amazing dramatic moment. If Qui-gon left the republic, what would that do to Obi-wan's mind! Dang you, Lucas! Wasted opportunity!

Well, Lucas is lucky he did kill off Qui-Gon, because there is no way Liam Neeson would have come back. He was pretty damn vocal about how much he hated the way Lucas made The Phantom Menace and that's why he declined to appear as Qui-Gon's ghost and we ended up with the Force ghost thing being slipped in so inadequately at the end of Episode III.