The bikes used to come with ball bearings. These would wear out and get "notchy" so we replaced them when this happened with tapered rollers. No more problem. Then some bikes came stock with tapered roller bearings and all was good.
Now I see that we are largely back to ball type bearings because the makers say the steering is more sensitive with them. I suppose they can make a case for that but it's nebulous at best.
But if your steering bearings don't act up and don't feel like they have a "notch" around center then I wouldn't sweat it. It's not a performance mod, it's a reliability and long life mod. But it takes good ball bearings something in excess of 30,000 kms to wear out. And maybe by 20,000 you should start checking now and then for bearing slop and any notchiness.