#1 To keep AJ Styles away from the Money In the Bank ladder match
Let's assume for a minute that AJ Styles was not in the title match at Money In The Bank. Chances are that he would be in the Money In The Bank match itself, and that presents a lot of problems for WWE.
The company prefers to have heels win the thing because then the element of a cash in always looms over a babyface. But the crowd would not take kindly to AJ Styles losing such a match. Which is why the idea could be to keep Styles away from the Money in the Bank ladder match.
We've seen members of the WWE Universe hijack the proceedings on more than one occasion. Remember the Royal Rumble that Roman Reigns won, where a chorus of boos rained upon him? WWE may not want this to happen during Money in The Bank.
Styles is also not a young man anymore and the match is more suited to people younger than him.