I respect your opinion, but what you wrote is a great example of WHY women should propose. You basically said that men often propose because they are almost forced - or demanded - to do so. How humiliating is it to realize that the guy only proposed to you because you told him you will only move to another city if they are married... Or because it's time to get a house. NOT because he loves you, NOT because he wants a family with you, but simply because "something changed" or a woman told him they had to be married to do certain things.
Your comment about "if you're having sex, why get married?" is even worse, lol. I have an article about a friend who's waiting till marriage to have sex. It's an excellent concept to protect yourself from men who would gladly sleep with you, but won't marry you, because why buy a cow if you can get milk for free. And I actually met quite a few women who left their partners because they wanted to enjoy the benefits of a marriage without getting married.