There's something that's been rolling around in my head for a bit. I'm just kind of thinking aloud. Maybe other posters have something to add?
"nice guys" are kind of like sluts.
It seems to me women crave emotional intimacy (validation, attention.. whatever you call it) from men, almost in the way men crave physical intimacy (poon) from women. They can't get this validation from other women, it must come from men.
And the man doesn't need to be an Alpha to provide this intimacy. Any man with reasonable status among other men will do. Much the same way a woman doesn't need to be deserving of a man's commitment for him to bang her.
Relationships are, broadly speaking, a trade. The man provides emotional intimacy, the woman provides physical intimacy. A slut is not respected because she provides physical intimacy without requiring emotional intimacy in return. She has sold herself cheap. A "nice-guy" provides emotional intimacy to a woman without requiring physical intimacy in return. He has sold himself cheap, and likewise is not respected.
Does this make any sense?