Why are steering stem nuts so goofy?

[JPaganel]

Is there some specific reason the steering stem uses these ridiculous nuts requiring a special spanner? Seems like they could have used a normal nut just as easily...

[CutterBill]

If they were hex nuts, they would still be so thin that you would need special thin wrenches.  That style of nut is actually quite common on all kinds of equipment.  Google for Spanner Wrenches...