#1 To boost Raw and SmackDown's ratings

As of now, we don't know if Brock Lesnar will cash in against Seth Rollins or Kofi Kingston. The only thing we know is that he is Mr. Money in the Bank and he has an opportunity to win another world championship in WWE.
The fans don't want to see him in WWE, and they tend to boo The Beast whenever he appears. However, we should accept the fact that whenever Lesnar makes his appearance, ratings touch the sky. Fans who boo him ultimately enjoy seeing The Beast even if he appears once in a while.
WWE doesn't want these wrestlers back - Find out now!
Now that The Conqueror has won the Money in the Bank briefcase, it wouldn't be shocking if he appears multiple times on Raw (or SmackDown) before actually cashing it in. WWE could announce his appearance in advance so that the fans could catch the action while it's live.
Eventually, he could end up winning another title and occasionally appear on WWE whenever Vince wants him to. While we know, it shouldn't happen, but since it has happened many times, there's a possibility that history will repeat itself.
Big name returning at Evolution? More details HERE