10 Years of Marriage Equality Support Series: Marriage, Procreation and Same Sex Marriages: Part 1

Some people have argued that, as marriage was clearly designed for procreation, same sex couples just do not belong in marriage. They also say that allowing same sex couples to marry will mean that marriage is redefined to be about the emotional needs of adults.
I agree that marriage was clearly designed for procreation and it isn't just about love. Therefore, I do not support the idea of 'freedom to marry', I only support 'marriage equality'. There is no absolute freedom to marry just anybody you like, and there should not be. But including same sex couples in marriage is not about this. Marriage is a specific institution, and it should be kept that way.
The core of marriage is about procreation, it is the reason marriage exists. However we do allow infertile couples to get married. Anti equality advocates argue that this is because they still 'resemble' the arrangement for procreation, a wishy-washy argument that may also apply to at least some gay couples, e.g. butch-femme couples, and may be even applied to all gay couples since all of them are in conjugal relationships. I would rather argue that we let infertile couples marry because we are a decent society, and do not wish to exclude infertile people from marriage, so we have decided that infertile couples who otherwise live in a marriage like commitment are allowed to be married, even when they cannot procreate. We have made this decision as a society because the cost of maintaining absolute purity regarding marriage and its roots in procreation are not worth the discriminatory outcome that would taint our society so badly. The same case can be clearly made too regarding same sex couples.
More importantly, including infertile couples in marriage has not affected the central idea that marriage is for procreation, making the 'cost' of such inclusion only technical, and the case for excluding them only palatable to ideological purists, and not to the majority of the population where practical outcomes matter most. This is because infertile couples are a minority, and extending inclusiveness to them does not affect the central idea of marriage. To believe that by including gay people, comprising 2% of the population, in marriage is going to change what marriage is, is a ridiculous proposition. To uphold ideological purity now is even more ridiculous, when it has already been lost by including infertile couples. Excluding a whole class of people from an important institution in society because of a characteristic they were born with clearly taints the conscience of our society, and is clearly not worth it when the benefits are only to maintain some ideological purity, that has already been lost anyway.
A related argument against same sex marriages is that heterosexual marriages are 'complementary' whilst homosexual relationships are not. However, it is the same argument as the one above, just without spelling out the specifics. I cannot see where all heterosexual marriages are complementary and gay relationships are not, except in the field of procreation. Again, in the field of procreation, infertile couples can be said to be not strictly 'complementary' in function again, at least in some cases (e.g. where there is no womb for creating offspring in the woman). Again, to insist that this 'complementary' idea be an absolute requirement of marriage in every case is just another form of ideological purity over practical outcomes, and pertaining to an ideological purity that has already been lost anyway.