#4 To shine the spotlight on the actual tag teams
Right now, on RAW, the tag team titles rest around the waists of Braun Strowman and Seth Rollins. An absolutely stacked roster of tag teams has nothing to do at all when they should be taking each other on for the prestigious titles. And as we've seen on social media, there's a whole bunch of fans that don't seem too happy with this decision at all, really.
On the other hand, you have AEW bring in teams like LAX, while Lucha Bros and The Young Bucks put on matches that blow the mind completely! Therefore, it is necessary to not repeat the same on SmackDown Live. At least on the blue brand, The New Day and The Revival are likely in the title picture for now.
Top name doesn't want to enter the WWE Hall of Fame. More details HERE.
Inserting Bryan and Rowan into the tag team title picture again would have just decreased the morale of the locker room completely, which is why Vince McMahon probably split them up so that both men can go their separate ways.