#3 Mainstream attention
It's no secret that WWE is a sucker for mainstream attention and they have gone out of their way countless times to make sure they have it during WrestleMania season. Of course, that's not really a bad thing, especially since it's the company's biggest time of the year. It creates a situation where they always have to top themselves.
For example, how is WWE going to top last year's WrestleMania, which featured a Triple Threat match for The Women's titles between Ronda Rousey, Becky Lynch, and Charlotte Flair? Not only was it the first time a women's match had ever headlined the show, but it was also one of the best examples of WWE using mainstream appeal to court viewership.
Now that doesn't mean that Rousey didn't belong in that match, but it does show how far WWE is willing to go to integrate mainstream names into their programming. That's why Velasquez versus Lesnar is such a great match. It capitalizes on mainstream appeal, would be fun for The WWE Universe to see, and makes for a great story!