I think NZ, AUS etc is very lenient with its laws already. Unfair is what happens in most countries where being gay is considered illegal.
We're lenient with our laws? Do you think we should be saying "oh thank you mr law maker for allowing us to be who we are without the risk of being thrown in jail or killed because we prefer carrots to rug." Which would you rather say when introducing your partner, "he/she is my husband/wife" or "he/she is my life partner"
My view is that marriage is something that happens in a church (and not a registry office, garden etc).
I don't see anything wrong with using the term husband/wife though if you've had a civil union. Partner is such a stupid term as it sounds like you are in business with them. Life partner is just a clumsy fix.
Husband/wife or boyfriend/girlfriend is much more easily understood.