#1 To capture the Total Divas crossover fanbase
WWE is always looking to tap into a crossover audience. Ronda Rousey has brought eyeballs to the product with her appearances in the world of Mixed Martial Arts and the silver screen. Similarly, Chris Jericho and Dolph Ziggler bring the music and comedy fraternity to the wrestling world, through their ventures outside the ring. Total Divas is one such highly successful device.
The fanbase that watches Total Divas probably does not care about the in-ring product at all. Rey Mysterio and Andrade could put on the match of the century and they would not care! They are likely to watch RAW and SmackDown Live if they were served storylines with a scandalous twist.
WWE is a variety show. There is something for everyone and that is why RAW and SmackDown Live have lasted so many years.
Feel free to agree or disagree with my points!