I'm going to have to disagree with you there.I feel the clone wars actually added a more detailed origin and tried to make her more "human", more so after the annihilation of her tribe. I like that she became a bounty huntress. She went from wannabe sith to trying to find her place in the galaxy. In the comics Obi-Wan says he doesn't consider her truly evil, just misguided and afraid. And the nightsisters din't train her to be a killing machine, Dooku already did that. All the nightsisters did was help her attempt to assassinate Dooku.
Season 5, Ventress' fate seems to be going closer towards that of the dark horse comics, but that's just fan speculation based on the 2 previews.