Everyone knows about the Jedi funeral pyre scenes in Return of the Jedi and The Phantom Menace. They're iconic and awesome. After my dad was cremated, my grandmother was upset until I reminded her that cremation is the Jedi custom. Then she got all excited. Yes, that is how geeky we are.
Here's the thing: HOW HORRIFYING WOULD IT BE TO WATCH THE BODY OF SOMEONE YOU KNEW BURN UP?
Seriously. I mean, in The Phantom Menace, we only see the flames surround the edges of Qui-Gon's head. His right boot is starting to crumble, but otherwise he looks fine. Not long after the camera cuts away, however, the onlookers were probably staring at his sizzling, blackened flesh peeling slowly off his face. Eww. Not to mention the smell...
Now, Vader was contained within his black armor. He probably cooked all nice and neatly inside there like chicken in an oven. But Qui-Gon? That's just nasty.