Same question here. I can get why the live photo's are a bit stuttery as the commenter above me mentions. When capturing live photo's, the camera starts recording 1.5 seconds before you actually tap the shutter. The stuttery part could perhaps be a result of the buffer size - but these are pure speculations as I actually don't know much about electronics and software.
What's bothering me is that there is indeed no backwards animation of the live photo when you release your finger from the screen, or at least why it isn't available as a setting for your lockscreen wallpapers. I design my own wallpapers, so it would be very cool to make an animated one. The idea in my mind would probably work best if it could animate backwards afterwards...