#1 A Way to get the title off of Seth Rollins

In all honesty, Seth Rollins's run at the top won't last forever and the inclusion of Sami Zayn in the Universal title match at Stomping Grounds is a way to ensure that Rollins loses the title without looking weak in defeat. It also gives WWE a chance to finally establish Corbin as the company's biggest heel, which is a long time coming after what he's been through.
In fact, between him losing the Money in the Bank briefcase and being ousted as the Raw general manager, this man's main event push is a long time coming. Beyond that, it would be extremely refreshing for the WWE Universe and even sets up another babyface to one-day take the belt from Corbin.
In the end, there are a lot of capabilities at play with Baron Corbin as Universal champion and it would be a logical way to establish new stars whether they be babyfaces or heels. It also gives WWE a chance to do something different with Seth Rollins and maybe utilize him to help build another one of Raw's divisions.