Poison was, as far as I know, NOT intended to be a futa. She was just an ass-kicking female villain (with her sister). It was indeed deemed inapropriate to depict a male beating up a woman in the west (mostly USA), so they were replaced by different sprites, and where not possible they changed it so that they were transvestites so you were really "beating up men" (though nowadays THAT would be transphobic whereas hitting girls would be fine if the girls can fight back as strong women etc.). Later, the stories got all mixed up and Poison became one of four things: A woman, a transvestite, a transexual or a dickgirl...
As a straight male, I only find the first atractive, but I have no problem with games depicting any of the categories as NPCs. I do however find it frustrating that censorship keeps messing with the artist's original vision. And that is not restricted to Poison.