He hasn't really had a "big match" win since Reigns in the Ambulance Match. He lost to Brock, was eliminated in the Chamber, didn't win the Rumble (GRR is ehhhh since they don't have him carrying around the Saudi Arabian Championship title), Wrestlemania was that bullshit. I think they felt like they needed it to keep him from cooling off.

Whereas KO is KO, and they feel they can fire him up whenever.