The problem is that there aren't actual human beings in video games - there are mostly victims, some superheroes, none of the characters have much vocabulary, rarely do any have real emotion. Creatures who aren't real can't be sexy - the most they can do is APPEAR sexy - like a sad woman pretending a boob job will make her happier. Calling Lara Croft sexy is missing the point that she's an archaeologist who murderers hundreds of people and destroys the very archaeological site that she's supposed to be preserving. That's not someone I want to have anything to do with regardless of what she *looks like*. That's a failure of both the duties of an archeologist and the morality of being human. Likewise, Bayonetta is a superhero, she's not human so she ought not be sexy to *human beings*.
Developers don't take their creations very seriously. Great writers personally connect with their fictional constructs to the point where they become real to the writer - they then present them as real people in the novel, giving them and their readers the ultimate respect.
Cynical video game developers pander to what they suppose gamers want and have no respect for their characters or their players. So we get dehumanized nobles who "save the world" by being granted superhero powers by the developer - if they really respected their characters they would present them as human beings - no superpowers, real problems and having to face the consequences of one's actions, no reload function to "make every wrong right".
Consider the recent Avengers movie. The characters don't take matters too seriously, and why should they, when they are mega super-powered and have the privilege of being the protagonists in a Hollywood movie, so of course things will turn out well for them. Despite the "fate of the world at stake", it was more like they were playing throughout the film. Playing is what people do when there's nothing at stake.
Human beings deal with joy, despair, failure, hope, love, and forgiveness, for starters. Game players deal with murder strategy, inventory management, reload function judgement, fun maximization.
Compare the connection that different artistic mediums have to what it means to be human. Great books are those which make us more human. They teach us about the world and ourselves. Great movies and television shows likewise. Comic books and video games are the first artistic mediums to not be about humanity, but superpower. Games only rarely teach us about ourselves or the world. They mostly teach us what it would be like to have superpowers, to have a stellar physique despite zero gym time, to be able to go back in time to any point even after death, to not have to eat, rest, take a shit, to not have friends or family, to only talk to people in the service of saving the world, to be happy about shooting a gun continuously murdering hundreds, sprinting like the wind, slashing one's way through thousands of enemies, being declared Glorious Hero and smiling at another fake universe saved, more unreal people pleased in another plastic world.
People find beings similar to themselves sexy. Humans like other humans. Superheroes like superheroes. So if game developers want to appeal to human beings, instead of the superheroes they crave as customers but which they simply aren't going to find in the real world, then they need to put real humans in their games, just like every serious writer begins by making his fictional characters real *to himself*, before he can ever make them real to someone else.