The argument is misidentified. Gay people get married in every state. Nobody is going to get arrested for performing the ceremony, nor will they. It is legal, it is done, and nothing we say here will change that.
The argument is whether we should legally recognize the relationships and what benefits they should obtain through it, not whether they can do it. They already do.
Can you tell me what it is about the definition in the 60s that make it "perfect"? What benefit does society derive from denying simple things like allowing their spouse to visit in the hospital without having to pay money for a lawyer to write up a power of attorney, the sharing of medical benefits, and rights of inheritance?
Basically what benefit do we get from making their lives more difficult based on the "perfectness" of an old definition. There is nothing in "tradition" that makes it perfect and unchangeable. Traditions change all the time, as well as definitions all without causing doom to a society.
There was a time where the definition had nothing to do with choice. Where others made the choice of whom you would marry, does that mean we should go back to those days? Was it more perfect because it was an older definition and based in centuries of "tradition"?