#1 To give Rose and Deville a separate platform
Mandy Rose got her shot at the Smackdown Women's title at Fastlane but lost the match due to mishandling of the ring skirts by Sonya Deville. This lead to Mandy getting upset with Deville and doing the same mistake during Deville's match with Asuka after which Rose walked off.
Tension is rising between the members of Fire and Desire and they can come to blows in the coming weeks. And in most probability, if either of the members wins the fatal four-way match, the other is bound to join, making it a triple threat which dilutes its RAW counterpart's program.
Even if WWE goes with the triple threat, it devalues the title as the rivalry between the two becomes the major focus of the match and not the title itself.
Mandy Rose and Sonya Deville should compete in the women's Battle Royal where they could further their feud and one of them could even win the whole match.