I was hoping to see Luke ‘ignite the green’ and all that, but that was under my assumption that Rey would be using the blue one. When they team up to go kick ass, as obviously what was going to be happening in this movie, Luke would naturally be using his trusty old green saber.
However, in the context of the movie that was made, the blue saber is the right choice. The movie begins with him sordidly chucking it over his shoulder, and concludes with him accepting and using it.