You don't control the movie. If you controlled the camera, it would not feel smooth at all. And no, 30 fps is not playable at all. You can't even properly aim at that FPS. Sure, it will launch the game on ultra settings, but no way it will be an enjoyable (playable) experience.
Look here: http://frames-per-second.appspot.com/
Look at the ball that's moving at 30 fps. It's all blurry and hard to see. If a ball is that hard to see, how can I see an enemy that's going to shoot me and shoot him before that at 30 fps?
Lastly, who the hell would buy Battlefield 3 to play single player?