My experience with Vader was similar. It was my friend who really wanted to meet him, so I stood back and let him go up solo. Vader would sort of face the camera, then turn to my friend and play a pre-recorded line and make a gesture. Then I hopped in and we took 2 pics and then Vader went into his spiel again and even walked my friend to the exit and played a final recorded comment. When we checked the pictures later there was one where he face the camera with my friend, the 2 I was in and then several awkward pics where they were sort of looking at each other or mid gesture.
I can see it both ways. After waiting in line for 20 minutes or more you want some interaction. And they've themed the rooms, so it's cool that the CMs are somewhat "in character," but I would also like the option to just say, go in, do 2 poses, and leave if I don't want to play act the whole thing every time. I think if Kylo Ren was giving hugs, some people might complain. Though, I mean, if I happen to dressed as Han, I'd want a hug, with a red lightsaber sticking out behind me.