Greatness is over-rated.
Ciao
I disagree, or I would change this statement to "Greatness is too often assigned, and rarely achieved".
The key is design innovation, feeling as though you are playing something unique, exciting and/or different. For whatever reason, I thought of the 9th hole at Pacific Dunes first. Especially when you play to the lower green, that hole is unusual. You have to drive the ball to carry the imposing wall of sandstone to reach the fairway, which slopes down rather sharply to the small, undulating green. I don't know if it's still there, but there used to be a little gorse bush guarding the left side of the green. In the summer, the two shots are playing decisively downwind. Those are two exciting and unusual shots. It's hard to get the distance right on the second shot, downwind from a downhill lie.
By the way, I like the lower green at Pacific Dunes #9 way better than the upper green. I think the hole is far more interesting played that way. You also get the bonus of playing the 10th hole from the lower tee.
That's one reason why North Berwick is so great. You just see stuff that is new and exciting and challenging. It grabs your attention and stokes your interest. When you see something new and different, it makes golf more fun.
I say great courses offer bold and innovative hole designs.