#3 Needs big names
It's no secret that WWE relies on their top Superstars for big four pay per views and that is exactly what they are doing here with Cain Velasquez. Not only does this move create a completley new dynamic for the entire match, it also gives WWE a level of mainstream press they wouldn't have gotten otherwise.
If nothing else, Velasquez is one of those few Superstars with crossover appeal - a guy that can get the mainstream media's attention and use that to bring in the casual viewer. The company can then capitalize on this cross promotion, bring in new fans and create historic moments in the process.
In the end, WWE needed big names for this pay per view match and while guys like The Undertaker, Sting, Triple H, Shawn Michaels, John Cena or even The Rock would all be fantastic picks, it is someone like Velasquez that is going to give the company an edge when it comes to mainsteam attention.