If I have a spare Ring of Royal Grandeur, I give it to my follower so they can wear two pieces of Sage's set and two pieces of Cain's (chance for extra Greater Rift keystone) and get the three-piece bonuses of each. Gloves of Worship, Flavor of Time, Nemesis Bracers, and Occulus Ring all emanate, so I add them as well.
It seems like they wanted to up power creep into a full power walk with the emanation stuff. Basically more ways to get more powers on your characters. And with Ethereal items coming in the next patch, that's confirmed. More Power!