The Jedi Order has long since lost their way and naturally, entropy runs its course. The Sith had their run and soon fell. The Jedi did too. The Jedi fell into the same trap that the Sith did. This all happened under Master Yoda's watch and perhaps the few before him.
Qui Gon Jinn was the purest Jedi in that he listened to the Force. He listened to the will of the Force. He knew his role in things. He was the chosen one to discover the chosen one. Jinn would often get into disagreements with the Jedi Council because he didn't answer to the Council, he answered to the force.
There is no emotion, there is peace.
There is no ignorance, there is knowledge.
There is no passion, there is serenity.
There is no chaos, there is harmony.
There is no death, there is the Force.
This is why he was rewarded with the knowledge on how to live on through the Force.
This is also something that Master Luke Skywalker probably realized later on in his life and why the Jedi Order needed to remain history. This same truth is what he passed on to Rey.
Now that Qui Gon Jinn hairstyle that she has all makes sense.