#4 To make Charlotte Flair look strong
There are three women involved in the WrestleMania 35 Main Event match now. Like it or not, Charlotte Flair has been the golden girl for WWE ever since she was brought up from NXT. And unlike Ronda Rousey, Charlotte Flair will be a part of the Women's Division even after WrestleMania eventually comes around.
The story of this match was that Becky Lynch] would win it and go to WrestleMania at any cost. This is pretty much the main highlight from WWE Fastlane anyway, and the point of the whole pay-per-view, so to speak. Very little else of consequence actually took place during the course of the 5-hour show.
By having Becky Lynch on one leg defeat Charlotte Flair, it would make The Queen look incredibly weak. She would seem like a non-factor in the WrestleMania main event match, devaluing the legendary main event.