David F,
The bigger question is why does "straight" society suddenly want to assimilate a parallel society which was consciously built on a platform of separatism and an ideal of communalism and mutual aid?
All of the principles and the nomenclature of the marriage equality movement were constructed out of whole cloth during the latter half of the first decade of this century, this is a social justice issue manufactured by the social justice industry.
Look at the AME site and scroll through their partners:
http://www.australianmarriageequality.org/
This is a corporate agenda, Marriage Equality is to the new capitalist class what women's suffrage was to the old capitalist class, today's middle class reformers are channeling Richard Pankhurst and Constance Lytton.

Dear Jay of Melbourne,

I appreciate the comparison you made.

"Marriage Equality is to the new capitalist class what women's suffrage was to the old capitalist class, today's middle class reformers are channeling Richard Pankhurst and Constance Lytton."

Woman's suffrage is what we should have regardless of whether or not the old capitalist class supported it. We should have it because women should have as much say in public affairs as men.

Marriage Equality is what we should have regardless of whether or not the new capitalist class supports it. We should have it because Marriage Equality extends the recognition of a committed relationship to a part of society previously denied such recognition. People in a stable marital relationship are less likely to have health problems and are happier. This lessens the cost of mental and physical problems to society and increases happiness.

David F
In the UK 1409 same sex couples have tied the knot in the year since such unions became legal, that's 2818 people out of a population of some 53 millions and anecdotal evidence suggests that most of them had been together for years if not decades beforehand.
This isn't an issue of need, or discrimination or anything else, it's partly political tactics, to a large extent driven by new economy capitalist self interest and supported by the narrow demographic of the upper and middle classes who are also the shareholders in the corporate partners of Marriage Equality and the main political activists and body corporate of the major parliamentary parties.
The term "Doctor's Wives Issues" about sums up the great middle class causes, same sex marriage and LGBTIQ rights, climate change and support for illegal immigration.

Suse,

Then cruelty to animals is normal as I'm convinced that some people are born with a lack of empathy to animals.
Murder is normal because some people are born with a built in tendency to kill their fellows.

The fact that some men sodomize their wives doesn't make it normal, what's your take on a bit of marital buggery if the wife doesn't want to do it?

Sodomy is a perversion and to call the union of sodomites marriage is a denigration of a normal union.

Jay, the fact that this issue and others are supported by some sections of the middle class of our society, and it would seem in the case of gay marriage also strongly supported by other classes of society, that does not in itself make it an inherently dishonest cause. Unless you are still a believer in rigid class boundaries and still hold to the old 'class warfare' mentality of yesteryear.

Dear Is Mise,

Of course a sexual practice should only be carried on if all parties are in agreement. As far as anal sex goes I knew women who liked it. What is called a perversion to some is a source of pleasure to others. If you don't care for a particular expression of sex don't do it. If all concerned and involved are in agreement that a particular sexual practice is desirable it makes no difference that others may call it a perversion. Anal sex is not my cup of tea, but if others like it that's their business. I don't tell others what to do.

A wonderful bunch are the Persians
Who enjoy sex and other diversions
They have sex in the day
In the usual way
And reserve the night for perversions