ER-16 bearing doesn't fit on steering shaft
The bearing race is a hardened high carbon steel. Changing the shaft O.D. would be a lot easier.
Facory did find they could omit the lower bearing but...
The OEM box coupling doesn't allow as much movement as a universal joint. Without the lower bearing and with a universal joint the shaft could move around much more. Would that shorten the life of the pizzy little upper bearing... maybe.