Note: Minor spoilers ahead, obviously.
In an interview with People, director Rian Johnson said they threw it in for intimacy, and also because Adam Driver looked damn good after training for six months.
Despite that the scene ellicted some laughs - partially due to Rey's surprised reaction, and partially due to the way the scene was presented - almost everyone can agree that Driver was looking super sexy.
"It was just another way of kind of disrobing Kylo literally and figuratively a little bit more, and pushing that sense of these conversations becoming increasingly more intimate,” Johnson said. “Adam looks so damn good because he’d been training hardcore for the past six months for those fight scenes. I’m like, ‘Eh. He looks so good. We should put him up there.’”
Of course, Driver has gone nude/shirtless many times before, largely thanks to his role on Girls. He was also a Marine prior to acting, so, you know.
He is more suited to play Kylo Ren than we ever could have imagined.