IF you see little or no wear on the blade OD yet the bearings have failed on a new pull-type (not mounted) planter, I would say that either

A) someone is turning sharply with the row units still in the hard ground. This is something that the units are just not designed for, especially in hard ground. Ball bearings as used in opener assemblies are basically designed for radial, not side loads.

Planters with the lift wheels out in front of the toolbar have residue flow and other advantages but do create more side load on openers when turning with row units in the ground than the older configurations with lift tires between the row units.

or

B) Case has a batch of bad disc/bearing assemblies 

I believe all OEM planter manufacturers purchase riveted blade and bearing assemblies complete from one or more of a number of different possible suppliers of the complete assembly. Deere had a situation a couple years ago where the blades were cracking. Case may have a batch where the bearings are just not up to par for some reason, not greased sufficiently at assembly, poor bearing to begin with, etc. You might want to look closely at one of the failed assemblies, take it apart and see what manufacturer ID is on the bearing itself. See if there are signs of grease inside, are the balls brinnelled (flaking of the surface due to incorrect hardening) etc. This will give you more information to discuss with Case service people. 

Best of luck.

Jim at Dawn