Well, these satellations have nothing to do with aiding of the removal.They're just pieces of soft rubber. In fact, it's probably even harder to remove them using one or two screws. The castellations should help establishing a better oil flow towards the bearing, if I may believe the distributor of those oil seal.
I've looked real close on the picture from the Yamaha motor company, and it shows that part no 19, the oil seal, is indeed mounted with the "closed"side inwards.