The Rule of Law
When the law has been universally interpreted one way for centuries, it is blatant judicial activism to then decide to interpret it another way. It’s that simple. Any change in substantive interpretation should require a change in law. That is what “the rule of law” means as opposed to “the rule of man”. “Men” just reinterpret when they don’t like what something means rather than changing the actual words.
Ironically, your assertions regarding pairs, minors, incest being settled law is an appeal to that exact same principle of consistent interpretation, but the requirement that marriage was between a man and a woman was also settled law for centuries prior to this blatant reinterpretation.
Property and inheritance matters should be individual rights, not pair-wise rights, and they increasingly are with Power of Attorney, thanks in good part to the persistence of gays.
The remainder of legal marriage are subsidies and special privileges that are largely unjustified, particularly in a childless marriage. And while I do not believe that such discrimination on the basis of marriage by government is morally justified, until this very judgment, the uncertain potential for children and raising them was more than enough rational basis for discrimination.