One of the friends I've made since I started riding (in June of 2005) is a retired mechanic who finished his career as the head mechanic at Pratt and Whitney Aircraft Engines here in Ontario. He rides a 1976 Goldwing Ltd; he bought it new in '76.
He told me about the ball bearings in the head, and when I started to experience a bit of less than crisp high speed steering he suggested I change the old ball bearings to the tapered type. He had done the job on his Goldwing way back when. He also suggested the grease fitting. I have a lot of faith in my friend's abilities, and couldn't see any harm in putting in the fitting.
And yes, I did pump the steering stem full of grease. I don't imagine it will need much more for a long time. (When I disassembled the steering stem though, the original ball bearings had almost no lubricant left on them, and the races seemed to be wearing poorly as a result. For a buck forty-nine (Canadian), and about 5 minutes work, I figured it was worth it to never have to think about that problem again. That's what it accomplishes for me, anyway.