One thing I was conflicted about on this movie is the choice to use Driver as the actor at all. Visually, my image of Kylo Ren was just shattered when he took off his mask. He just...looks like such a child. Not literally, but, he's so young, his face looks so normal and kinda innocent. Even his voice is soft and maybe even a bit whiny. Guy just looked like he's straight out of highschool.
At first I was like "He does not look menacing at all" But again, it's like JJ Abrams watched the Plinkett reviews, and now I see it as a parallel to how they revealed Vader to be a sickly old man. Given how his character arc is about how he isn't the heartless badass he desperately wants to be, now I think that this was a very good choice, because his general character conflict is visually represented just by that one scene where he took off the mask. He wants to be Vader 2.0 and he's just...not.
You kinda answered yourself here (I know it wasn't a question ;-)
But the whole point is to show this guy is torn. He feels the pull of the light side but is trying to desperately stop it. He wants to go full dark side mode but knows he must kill his dad. He even looks innocent/conflicted, he's looks like he's on the verge of tears. Han also takes his words for a different meaning (I'll come home with you Dad). He really is a little boy in that moment for the audience and for Han.
But that actually adds to the character and his arc, he will do more and more nasty shit in the next movie to just keep going down that Dark side path.