If this movie went in any other direction it risked being bad. It risked doing something different that fans would have not liked. If J.J. went in a different direction, he could have butchered it more than that was already done with Prequels.

Kylo Ren's story is going to progress, this is a build up of what they are going to do. Since he had a balance of both light and dark.

SPOILER!!:
He got injured on the face, now he has a reason to wear the mask. He is going to get a Dark Side look now as he's angry and embracing it fully after what he did to his father. This is going to open a lot in the next two movies. I believe they are going to do another Vader where he is saved in the final movie and possibly I see him sacrificing his own life for someone (possibly Rey) against Snode). He is lost and in the middle of a light and dark pull throughout the movie, that's the only reason I see him having his "fits" as he's being influenced by both throughout the entire movie.