TheEraofAwesome has stated most of what I was going to say before me. Mankind was never a monster, he was a hardcore legend, which is something totally different. He could take a huge amount of damage, but he didn't deal incredible amounts of damage like a monster character would.
Also, Umaga dominated when he first came in, when he destroyed guys like Triple H and Shawn Michaels. His gimmick was monster, that doesn't mean he should dominate his entire career, it just means that he is feared for his power of destructive abilities. When Umaga came to the ring after matches, or during other people's matches, he destroyed guys and left them in the ring, much like what Kharma was doing. That is a monster.
As far as being a Kane/Mankind hybrid, I don't see it. Her having a trouble past could work but not handled this way. Kane's story when he came in was that his own brother burned him, what the hell is more troubled than that? Did he come out and cry? No, he came out and wanted to destroy his brother. She has a troubled past and cries? Not the signs of a monster.
Also, for everyone who is speaking on her TNA past, the WWE usually never mentions histories like that, so why would they now? This is supposed to be an entirely different character from Awesome Kong. If that was the case they would have just called her awesome kong and went from there. That's like Mankind crying because people beat him up when he was Dude Love, or Cactus Jack.
As far as Big Show goes, he was a joke when he came from WCW. There was one point where Undertaker tried to make him into a monster, but it never happened. He was always the soft big giant. He never even gave off the monster aura.
Overall, I just feel like she has all the ability and the build up to be a bad ass monster diva but instead, they'll turn her into something that any other one could have been. Why couldn't they have Kharma be a monster and have Beth Phoenix be the bi-polar diva thingy? Oh wait, they already did something like that with her, about her being crazy or something. My bad.