Marriage is a new thing, it has existed only for a few weeks now, since June 26. And the church has nothing to say about it - or no more than, let's say, the color and layout of the new 20 dollar bill.
It is true that we previously used the word "marriage," but were wrong because actually there was no marriage then. What we thought we were referring to no longer exists. Obergefell also refers to "marriage" in the past, but actually is confused - there was no marriage before June 26.
The meanings of words have to do with how they are used. Obergefell makes clear that - well, marriage is wonderful! Ethically, Obergefell goes into overdrive in what it does. It stipulates that marriage has to do with our very highest values, the words used to describe it are superlative, like a kind of ethical summum. So it is clear that marriage is wonderful, marvellous, spectacular. Probably everyone should have a marriage, or get married, or do whatever it is to rise to these wonderful ethical heights of virtue and goodness.
However, it just isn't so clear what marriage is.
Now, it is true that the church in the past is guilty of using the word "marriage" to translate cognates of ἐκγαμίζω - and translated γυνή with "wife," and ἀνήρ as "husband." But it was wrong to do so, because marriage is - this wonderful ethical state which we should all rise to - and - we really aren't clear on what a husband or a wife are, but we are mere church people, and not in the business of creating new wonderful spectacular ethical states. This is a thing which the judiciary branch does.
The church does indeed need to have a translation of the word ἐκγαμίζω - but it is exceedingly clear that the word ἐκγαμίζω in Scripture is not this wonderful, ethical, virtuous thing we call marriage. It is very, very different.
So the church - because of the obvious problem of lack of clarity in the past - should draw some lines, like making clear that no one will be married in a church building, nor ministers participate in officiating such ceremonies.
This wonderful, spectacular ethical state is also likely to change quickly - as we come closer to Full Marriage Equality, which has been an enormously important goal of our society, and has been important in giving us marriage.
So the church can go about its business, and allow the state to create, regulate, and officiate over this wonderful new thing it has given us.
Thus, the importance of recognizing that marriage is a new, wonderful thing.