#2 The Fiend needs the Universal Championship and a SummerSlam win more than Strowman
The Monster Among Men is a fighting machine who wants to deliver punishment and justice to his enemies. He doesn't need a championship to make him relevant. His character is similar to the likes of The Undertaker and Kane. Towering giants do not need championship gold; they want to beat people up. SummerSlam can help bring this point home.
Unlike Braun Strowman, Bray Wyatt's character is multi-dimensional. He likes to inflict pain upon his enemies, but also wants to take precious things away from them as well. The Fiend does have a keen liking for championship gold. He targeted then-Universal Champion, Seth Rollins, a few months after his debut. Wyatt wouldn't stop until he captured the Universal title at Crown Jewel last November.
With championship gold around his waist, Wyatt is unstoppable; he did a stellar job as Universal Champion. His rivalry with Daniel Bryan was well-received by the WWE Universe and their matches were fun to watch. With The Fiend as Universal Champion to close SummerSlam, WWE will be able to restore prestige into the Universal Championship.