It was ridiculous to have there be two things in the first place.
That I definitely agree with. It was terrible that it was not considered acceptable to simply allow same-sex marriage.
We want a legal contract that confers a range of mutual rights on us, protects our children and allows us to demonstrate our commitment to each other
Actually, no. I don't want to "demonstrate our commitment to each other". In actual fact, that is one of the main aspects of marriage I dislike. What I would like to do is to declare that my partner, the person I have chosen to buy a house with, sign my life insurance over, and would prefer to make decisions about my care if I am incapacitated, is the person who is my legal next of kin, in both the legal and non-legal sense of the word.
It would not be much time, trouble and cost. Its little more than a change in the wording of the legislation. The framework exists - it simply doesn't apply to heterosexual couples.
Yes, people who feel the same as me can get married. Many of us maybe eventually will.
But extending CPs to heterosexual couples is not a hassle. It is not time consuming, or expensive. Other countries manage it to.