I honestly don't see what people have against Roodaka. Of all the female Bionicle characters, she had a lot of personality, especially in the Web of Shadows movie. Her interactions with Sidorak made her all the more feminine. Granted, I felt the whole "engagement gift" idea was over the top in a bad way, but she served the purpose of being a queen of the Visorak. Sure, she had high heels, a slim design, long hair, and rahkashi heead boobs, but thats was all part of her character. Can you image somebody like gali Mistika(ugh) being a queen of something? I think not. She looked more like a titian sized Krekka.
Point is, Roodaka's design was something that she could pull off, because she was impressing sidorak. I loved roodaka's design, personally. But you need to see the character of Natalie Breez. If she is extremely flirty and such, then she would be better with a lighter design. (Or if she is a ninja like Lariska...ah Lariska... AHEM) But if she is a tough warrior like Gali then she is better suited with an armored up design such as the one she has now.
And regarding the robot not needing to be female aspect of thing, Transformers does it, and they pull it off. So I can see hero Factory pulling it off if the designers try hard enough.