#1 Sets up a dream Mania match

Apart from the aforementioned reasons, Sasha Banks and Bayley winning the women's Tag-Team Championships also achieves something else. WWE now have the chance to set up a dream tag-team match at WrestleMania - Sasha Banks and Bayley versus Trish Stratus and Lita.
Yes, I hear the argument that with Trish and Lita being part-timers, it would be a little obvious that Sasha and Bayley are retaining the titles. However, that doesn't mean that this isn't a dream match in its own right or the fact that it will probably be incredible.
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We all knew Brock Lesnar would be beating Goldberg at WrestleMania 33 when they wrestled for the WWE Universal Championship but that match was still an exciting hard-hitting match and it was easy for fans including myself to suspend our disbelief.
WWE needs to book Sasha and Bayley versus Trish and Lita at Mania. It's the highest profile match they can book for the women's Tag-Team Championships.