#4. The best option for the SummerSlam main event
SummerSlam looks like it's going to be a pretty good card this year and obviously, they need a main event to draw interest despite the show being sold out in Toronto. There aren't too many great options this year for a main event, so it makes sense that WWE would want to go with Rollins vs Lesnar.
They may not have had a proper match, but you can be assured that this time around, it's going to last a lot longer than just a few minutes. Seth Rollins is going to take a beating like never before and if it is the main event, that might mean that we'll see a motivated Brock Lesnar take charge.
Either way, Brock Lesnar is practically the king of SummerSlam with all the main events and big wins against The Rock, John Cena, Randy Orton, CM Punk, etc.