Agreed. Rian gave a good explanation in the special features of TLJ
Luke felt the jedi was doing more harm then good. He tried to train a new generation of jedi and failed as Kylo went to the dark side.
To keep the balance in the force there as to be an equal number of Jedi and sith. With the Jedi kicking around there will always be the sith. For everyone doing good there must be some doing bad to equal out or balance the force. So Luke realized this and decided to sacrifice himself for what he felt was needed to help save the Galaxy. That's why he said it was time for the Jedi to end and why he went into exile and closed himself from the force.
It's not the typical Luke from the OT because time passes and everything changes. History repeats itself so something needed to change to rewrite the future.