The Rumble isn't just about a title shot that other people just get handed at elimination chamber. It's about being in a Wrestlemania main event. In Kayfabe, a title match at Mania is worth more than a title match at other events.

I also like that it can help get things where we need for Mania. Last year Wyatt winning helped us avoid Cena vs Orton again (as bad as the match wound up being with Wyatt/Orton)

It helps keep the Rumble a little less predictable too when you know the title will be on the line in Elimination chamber.