The shifting animation wouldn't be that hard to figure out.
For folks with a clutch pedal, the arm could move down to the stick when you pressed the clutch - simple.
For folks without a clutch it's a bit harder. On the way up through the gears, the arm could come off the wheel as you approach the redline/shifting light, assuming that you're still on the throttle and not steering*. On the way down it'd need to be at low torque points, maybe just ahead of where an autobox would shift you.
It's fairly reasonable to assume that 99% of the time** in those situations you'd be just about to change gear. It might also count as a slight visual assist for anyone who wasn't sure
* Those are the only two things that jumped out to me which would stop you shifting - hard steering and (obviously) not accelerating. Maybe also assuming the car isn't sliding, since you might not be steering then but would be holding the wheel with both hands.
** Yes I realise that sometimes it might be wrong, but I can't imagine it would happen often enough that people would complain.