Im trying to look at it like this:
My PC, being disconected from the force is informed that he is the last of the jedi and out a moral/duty obligation must attempt to stop the sith. He seeks to reunite all the masters to combat the threat only to discover that the threat is in fact himself. And therefore the PC, due to his nature with the force ( empty shell - using others who can feel the force to increase in strength himself) becomes relativly stronger than anyone else using the force.
Also, I think that Nilihus' attack on Telos was more an action of desperation rather than a strategic move. He also fed off the force in others and had grown week since there was a lack of jedi/ force sensitve people to be found. Hence, the ease of his defeat was due to his weakened state.
I think at the end the game is more about unlocking the mystery of your own character rather than trying to save the galaxy. even though that is what happened when you beat Treya
Someone let me know if i something in that is obviously wrong