I know their use!

Its so you dont get your hand caught in the coupling. The steer shaft etc is smooth so wont catch the hand or clothes. But the bolts etc on the coupling could catch a sleeve or something. It could be dangerous as its a moving part!

.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
PS I know it would be near impossible as you only turn while driving lol. Just wondered how many people would go ah yeh that could be the reason!