No sir, you are missing the point. I've stated repeatedly that marriage isn't a right. No one is entitled to be married. It is a priveleged instittuion created by society for its own benefit. It was established for a specific subset of people with a specific intent in mind, namely raising children.
Neither homosexuals or heterosexuals are entitled to marry, and thereby obtain the benefits specific to that institution. A hetersoexual man cannot marry his sister or first cousin. He cannot marry more than one person. He does not have a right to marry whomever he chooses. Similarly, a man or a woman cannot currently marry someone of the same gender.
You conveniently wish to withdraw the mention of children from the discussion, but they are the singular overriding purpose for the institution. When you ask "what would it hurt" keep in mind that you begin the discussion with the premise that you wish to redefine the purpose for the whole institution in order to make your case. That represents more than just mild tampering