Fact 5: Dean wanted always to be dead, he was the one to jump always he heard the word "SACRIFICE" he had a lot of guilt with him and regrets we can noticed on episode "Unity" he couldn& #39;t continue with all those feelings...

Fact 6: Sam wanted to have a real life you know? have a family, kids and a dog even, since the beginning of the show we knew that...

Fact 7: If Dean would die in another produced way you know another God, archangel, angel, demon etc...Sam was forced to revenge that dead and continue that story, again that wasn& #39;t the point of the #SupernaturalFinale so this dead had to happen with a simple accident without help