The difference in hormones (testosterone vs. estrogen) the difference in physical strength and simple logistics made it that way. Submission complements dominance perfectly. With women being more suited to submitting to the stronger male who is more suited to dominance and protecting, you have what nature, >mother< nature intended. It's logical, logistical and practical in every way. The only reason people are able to deviate from it is because of modern laws and technology. I guarantee that if there were ever some sort of post-apocalyptic scenario, women would once again gladly submit to men who could protect them in exchange for submission.
Submissiveness in women is not a social contract. Role reversal is.

EDIT: Submission is cooperation. I do what I'm good at as does he. I'm just not going to fight, struggle, battle and compete to stay on par with someone who's too different to be equal to. Someone has to have final say so and if we ever disagree on something, a compromise isn't always possible with every single thing and that's why someone's way always has to prevail. But remember that the person who got their way is responsible for the outcome/consequences of at decision, be it good or bad. I don't know why you're always so threatened by my views. It's not like you're somehow going to be forced to do what I like. So why feel threatened and defensive instead of just realizing that people are different?