#4 This could lead to another World Championship reign
As Michael Cole made sure to mention at Money in the Bank on commentary, 82% of the Money in the Bank winners have successfully cashed in the Money in the Bank briefcase to win a championship.
Additionally, Brock Lesnar is undefeated in WWE's past few pay-per-views in Saudi Arabia while Seth Rollins only has a 67% winning rate.
Braun Strowman also failed at cashing in the Money in the Bank briefcase last year, and WWE likely does not want someone to fail to cash in the briefcase two years in a row.
Brock Lesnar's previous two Universal Championship reigns were stale and way too long. There is no reason to believe that another Lesnar title reign will be any different as he barely shows up on most pay per views, Raw, and SmackDown Live.
At a time where WWE's ratings are at an all-time low, WWE cannot afford to have the World Champion of either brand disappear from TV. Seth Rollins and Kofi Kingston have both earned their top spot and should not have to lose their titles to a part-timer.