Contrivances? With the exception of the "born from women who'd been killed by men" everything that happened to the pre-Flashpoint Amazons (rape, enslavement, persecution for not following social norms) is something that has happened to and still does happen to women. The story was following ancient history with mystical and fantastical elements thrown in. Again, why are you more accepting of the Amazons going out of their way to victimize men who have done them no wrong but not them staying on their island were they cannot harm anyone and cannot be harmed? Do you really hate them that much?
Furthermore, a woman running for President in the U.S doesn't mean that sexism has suffered a major defeat anymore than the U.S having a black President means racism is dying out.
Your examples of a small party of men and women is only really true in Western countries. It's an entirely different matter in many parts of the world.