I absolutely love the way you have asked this. Disinterest. Haha.
Gay marriage, as a term should be removed from our language. It should just be marriage, open to all, regardless of race, gender, social standing. Marriage should not cost anything, should not be used against someone and I would go as far to say that a divorce should be seen in the same way.
To be married involves signing a piece of paper anyway, and no one needs to sign a piece of paper to know that they love someone.
The legal benefits of marriage are mostly granted now in Australia to defacto and gay/lesbian/trans couples. Things have come a long way under Krudd.
Marriage should definitely allow anyone to marry any human being, there is no reason to disallow them, other than the Bible and that argument in Australia is preposterous as our Church and State are very, very separated. No way should the Bible be used to dictate things in Australia when Australia is the most multicultural country in the world.
Anything else?