If the hub is used backwards, the central core of the hub can unscrew from the outer shell. This can cause the hub to lock up, and it can easily damage the threads, making it impossible to reinstall the hub core. You'll be left stranded on the side of the road. This alignment is just as important as your pedal threads, which are right handed on the right pedal, and left handed on the left pedal. These threadings are different because if you had a right hand thread on your left pedal, the pedal could unthread from the crank. For exactly the same reason, the SON hub must be used with the connectors on the right side of the bike, the same side as your derailleurs and chain.