I could picture a two-seater, it would be useful to be driving around and have your buddy shooting everything for you. It's kind of hard to pull it off right though because I never liked how the aim is stationary, so when your driver turns or flips around you're constantly having to reposition your camera. What I especially hate is when games make it so that your vision is aligned with the bike, so every little twitch of the bike moves you around two. It makes pinpointing your target extremely difficult. I don't know what the sweet spot would be between these two but maybe if you've moved the camera in the past 2-3 seconds your vision won't change with the bikes movements.