I'm generally not a fan of the match format but yes I can see where you're coming from. I think Ronda is better than not good as it happens but she's certainly a step down from the other 2 involved.They need Charlotte in the match. Or rather, Ronda needs her because she is Not Good and one can't expect Becky, as good as wrestler as she is, to carry a novice like Ronda to a five-star match. Putting Charlotte in there takes the pressure off Ronda so she can play to her strengths, and Becky and Charlotte can have their own WrestleMania moments. The feud was between the two of them to begin with, which everyone seems to have conveniently forgotten. The triple threat is a win-win.
Perhaps I'm being parochial and I know that Rousey has a serious amount of mainstream appeal but this match doesn't get this spot without Lynch, she was the best character on WWF TV all last year. I'm chuffed for her the same was I was for Bryan getting to the main event.