I'm not surprised some people are disgusted by the idea of marriage - I mean, you could be legally raped within it till the early 1990s, even if separated; you couldn't own anything if married until less than 150 years ago; and only a little further back, the law actually laid down that you could be reasonably chastised as long as the stick was no thicker than your husband's thumb. And then there was the cheering fact that you had no legal status at all. Blackston said in the 16th century that, "'Man and wife are one person under the law, and that person is the man.' Nice.
But... I wouldn't buy a house with dh, knowing we both wanted kids, without getting married. That's not because I don't trust him, it's because I studied law. Every woman in every case had a guy she thought she could trust, and then when they split up - oops. Suddenly she couldn't. And marriage was the best protection against exploitative, deadbeat arses.
Seeker, not only do most people not plan their lives out that way (cohabitation, unlike marriage, requires no definite decision; you can drift into it), it also doesn't cover every eventuality. You get half the house, great, but if you have a tiny baby all you're entitled to is child support, if unmarried. If you have a small baby and you're married, you're entitled, as a rule, to occupy the family home while they're small if that is financially feasible, and to spousal maintenance until it's reasonable to expect you to return to paid employment.
There's also the fact that most people in this country think there's such a thing as common-law marriage, and just don't know the gulf between rights for an ex-wife, as opposed to ex-girlfriend. Rebecca Bailey-Harris did some research showing it was 60 odd percent, I think. That means they don't sort paperwork out, because they don't know they need to. On top of which, marriage is a flexible contract, that adjusts with circumstances. Property shares, wills, etc. are rigid; they don't change as your lives do.
Australia has what they call "de facto" marriage, which gives certain rights after a certain length of time. Until we have something like that over here, I'd never have kids without marrying... unless I were the richer party! Because marriage these days protects the poorer party, usually a woman, when historically it obliterated women's identity/rights almost completely.