It's not that simple. THE CHURCH of old is hardly the same as today's strip-mall, roll-your-own church structure. Leave the ceremonies aside, in prior days the Church imposing excommunication for divorce was a serious penalty. A priest refusing to marry, didn't mean that you needed to go to Vegas instead, it meant you couldn't be married period.
You seem to view the Church (and modern state's) role as largely functionary and administrative. But the missing role (in both cases) is moral.
Not that the modern state is a bastion of morality of course. It just happened to internalize, formalize, and beauracritize an ancient moral institution. I'd love to see the state out of the picture. I just don't want this urge used as an excuse to devalue marriage itself. And since the state was the reason the Church became a mere formality in this issue, it's hardly proper for the state to abandon what it usurped and then blame the Church when it doesn't turn out so well.
So your argument is:
1. The state usurped the institution of marriage from the Church, where it rightfully belongs
2. The state devalued the meaning of marriage
3. The state should continue to license this activity
That doesn't make a lot of sense to me.